(i) Lyophobic sol is protected. (ii) Lyophilic sol is protected. (iii) Film of lyophilic sol is formed over lyophobic sol. (iv) Film of lyophobic sol is formed over lyophilic sol. Correct...
Which of the following colloids cannot be coagulated easily?
(i) Lyophobic colloids. (ii) Irreversible colloids. (iii) Reversible colloids. (iv) Lyophilic colloids. Correct Answers: (iii) Reversible colloids. (iv) Lyophilic colloids. Explanation:...
Which of the following substances will precipitate the negatively charged emulsions?
(i) KCl (ii) glucose (iii) urea (iv) NaCl Correct Answers: (i) KCl (iv) NaCl Explanation: KCl and NaCl are the substances that can precipitate the negatively charged...
An emulsion cannot be broken by __________ and ___________.
(i) heating (ii) adding more amount of dispersion medium (iii) freezing (iv) adding emulsifying agent Correct Answers: (ii) adding more amount of dispersion medium (iv) adding emulsifying...
Which of the following statements are correct?
(i) Mixing two oppositely charged sols neutralises their charges and stabilises the colloid. (ii) Presence of equal and similar charges on colloidal particles provides stability to the colloids....
H2 gas is adsorbed on activated charcoal to a very little extent in comparison to easily liquefiable gases due to ____________.
(i) very strong van der Waal’s interaction. (ii) very weak van der Waals forces. (iii) very low critical temperature. (iv) very high critical temperature. Correct Answers: (ii) very weak van...
Freundlich adsorption isotherm is given by the expression x/m = kp1/n which of the following conclusions can be drawn from this expression
(i) When1/n= 0, the adsorption is independent of pressure. (ii) When 1/n = 0, the adsorption is directly proportional to pressure. (iii)When n = 0,x/m vs p graph is a line parallel to x-axis. (iv)...
Which of the following statements are correct about solid catalyst?
(i) Same reactants may give different product by using different catalysts. (ii) Catalyst does not change ∆H of reaction. (iii) Catalyst is required in large quantities to catalyse reactions. (iv)...
Which of the following option are correct?
(i) Micelle formation by soap in aqueous solution is possible at all temperatures. (ii) Micelle formation by soap in aqueous solution occurs above a particular concentration. (iii) On dilution of...
Which of the following phenomenon applies to the process shown in Figure?
(i) Absorption (ii) Adsorption (iii) Coagulation (iv) Emulsification Correct Answer: (ii) Adsorption Explanation: Adsorption is the process that can be applied to this...
Which of the following process is not responsible for the presence of electric charge on the sol particles?
(i) Electron capture by sol particles. (ii) Adsorption of ionic species from solution. (iii) Formation of Helmholtz electrical double layer. (iv) Absorption of ionic species from solution. ...
Which of the following curves is in accordance with Freundlich adsorption isotherm?
Correct Answer: Option (iii) Explanation: According to the Freundlich adsorption isotherm, the option (iii) represents the proper graph.
Which of the following process is responsible for the formation of the delta at a place where rivers meet the sea?
(i) Emulsification (ii) Colloid formation (iii) Coagulation (iv) Peptisation Correct Answer: (iii) Coagulation Explanation: The Coagulation is responsible for the formation of the delta at a...
Arrange the following diagrams in the correct sequence of steps involved in the mechanism of catalysis, in accordance with modern adsorption theory.
(i) a → b → c → d → e (ii) a → c → b → d → e (iii) a → c → b → e → d (iv) a → b → c → e → d Correct Answer: (ii) a → c → b → d → e Explanation: According to the modern adsorption theory, the...
The values of colligative properties of the colloidal solution are of small order in comparison to those shown by true solutions of same concentration because of colloidal particles __________________.
(i) exhibit an enormous surface area. (ii) remain suspended in the dispersion medium. (iii) form lyophilic colloids. (iv) are comparatively less in number Correct Answer: (iv) are...
A colloidal system having a solid substance as a dispersed phase and a liquid as a dispersion medium is classified as ____________.
(i) solid sol (ii) gel (iii) emulsion (iv) sol Correct Answer: (iv) sol Explanation: A colloidal system having a solid substance as a dispersed phase and a liquid as a dispersion medium is...
Which of the following electrolytes will have maximum coagulating value for AgI/Ag+ sol?
(i) Na2S (ii) Na3PO4 (iii) Na2SO4 (iv) NaCl Correct Answer: (ii) Na3PO4 Explanation: Na3PO4 is the electrolyte that has maximum coagulating value for AgI/Ag+ sol.
Freshly prepared precipitate sometimes gets converted to colloidal solution by ___________.
(i) coagulation (ii) electrolysis (iii) diffusion (iv) peptisation Correct Answer: (iv) peptisation Explanation: Freshly prepared precipitate sometimes gets converted to colloidal solution by...
The method by which lyophobic sol can be protected.
(i) By the addition of oppositely charged sol. (ii) By the addition of an electrolyte. (iii) By the addition of lyophilic sol. (iv) By boiling. Correct Answer: (iii) By the addition of...
Which of the following will show the Tyndall effect?
(i) An aqueous solution of soap below critical micelle concentration. (ii) An aqueous solution of soap above critical micelle concentration. (iii) An aqueous solution of sodium chloride. (iv) An...
At high concentration of soap in water, soap behaves as ____________.
(i) molecular colloid (ii) associated colloid (iii) macromolecular colloid (iv) lyophilic colloid Correct Answer: (ii) associated colloid Explanation: At high concentration of soap in water,...
In which of the following reactions heterogeneous catalysis is involved?
(a) 2SO2(g) + O2(g)→ [NO(g)] 2SO3(g) (b) 2SO2(g) → [Pt(s)] 2SO3(g) (c) N2(g) + 3H2(g) → [Fe(s)] 2NH3(g) (d) CH3COOCH3(l) + H2O (l) → [HCl(l)] CH3COOH (aq) + CH3OH (aq) Correct Answer: (a)...
Based on data given below to predict which of the following gases shows the least adsorption on a definite amount of charcoal?
Gas Critical temo./K CO2304 SO2630 CH4190 H233 (i) CO2 (ii) SO2 (iii) CH4 (iv) H2 Correct Answer: (iv) H2 Explanation: H2 is the gas that shows the least adsorption on a definite amount of...
Which of the following an example of absorption?
(i) Water on silica gel (ii) Water on calcium chloride (iii) Hydrogen on finely divided nickel (iv) Oxygen on the metal surface Correct Answer: (ii) Water on calcium chloride Explanation:...
In physisorption adsorbent does not show specificity for any particular gas because ______________.
(i) involved van der Waals forces are universal. (ii) gases involved behave like ideal gases. (iii) enthalpy of adsorption is low. (iv) it is a reversible process. Correct Answer: (i)...
Physical adsorption of a gaseous species may change to chemical adsorption with ______________.
(i) decrease in temperature (ii) increase in temperature (iii) increase in surface area of the adsorbent (iv) the decrease in surface area of the adsorbent Correct Answer: (ii) increase in...
Which of the following is not a favourable condition for physical adsorption?
(i) high pressure (ii) negative ∆H (iii) the higher critical temperature of adsorbate (iv) high temperature Correct Answer: (iv) high temperature Explanation: The high temperature is not a...
Which one of the following is not applicable to the phenomenon of adsorption?
(i) ∆H > 0 (ii) ∆G < 0 (iii) ∆S < 0 (iv) ∆H < 0 Correct Answer: (i) ∆H > 0 Explanation: ∆H > 0 is not applicable to the phenomenon of adsorption.
The extent of adsorption of adsorbate from the solution phase increases with ________.
(i) increase in the amount of adsorbate in solution. (ii) the decrease in surface area of the adsorbent. (iii) increase in temperature of the solution. (iv) the decrease in the amount of adsorbate...
Extent of physisorption of a gas increases with ___________.
(i) increase in temperature. (ii) the decrease in temperature. (iii) the decrease in surface area of the adsorbent. (iv) the decrease in strength of van der Waals forces. Correct Answer: (ii)...
The term ‘sorption’ stands for ____________.
(i) absorption (ii) adsorption (iii) both absorption and adsorption (iv) desorption Correct Answer: (iii) both absorption and adsorption Explanation: SORPTION - Both absorption and...
Which of the following interface cannot be obtained?
(i) liquid-liquid (ii) solid-liquid (iii) liquid-gas (iv) gas-gas Correct Answer:(iv) gas-gas Explanation: The gas-gas interface cannot be obtained.
At the equilibrium position in the process of adsorption ___________.
(i) ∆H > 0 (ii) ∆H = T∆S (iii) ∆H > T∆S (iv) ∆H < T∆S Correct Answer: (ii) ∆H = T∆S Explanation: At the equilibrium position in the process of adsorption, ∆H =...
Which of the following process does not occur at the interface of phases?
(i) crystallisation (ii) heterogeneous catalysis (iii) homogeneous catalysis (iv) corrosion Correct Answer: (iii) homogeneous catalysis Explanation: The homogeneous catalysis do not occur in...
Why in the redox titration of KMnO4 vs oxalic acid, we heat oxalic acid solution before starting the titration?
We heat the oxalic acid solution because without heat it is a slow process as much more energy than the activation power needed to react. Therefore to increase energy, the temperature should be...
Why can’t molecularity of any reaction be equal to zero?
Zero molecularity means that there is no reactant, therefore the reaction will not be possible. So if there is a reaction then its molecularity will be greater than the zero.
Why molecularity is applicable only for elementary reactions and order is applicable for elementary as well as complex reactions?
Molecularity works only in the elementary reaction as it is a single reaction and the rate depends on the concentration of each molecule. And in the case of complex reactions there are many...
Why can we not determine the order of a reaction by taking into consideration the balanced chemical equation?
Order of a reaction is involved in a reaction. In complex reactions, rate and order of the reaction depend on the slow reaction, so in such cases, the order does not depend entirely on the balanced...
Thermodynamic feasibility of the reaction alone cannot decide the rate of the reaction. Explain with the help of one example.
The thermodynamic feasibility of reaction alone cannot determine the rate of reaction because in order for a reaction to occur it is important that the molecules have a greater potential than the...
Why does the rate of any reaction generally decrease during the reaction?
The reaction rate decreases because the reactants will continue to be converted into products. The reaction rate always depends on the concentration of the reactants.
Why is the probability of reaction with molecularity higher than three very rare?
For a response to have more than three molecules, the correct position is not possible which makes this reaction unusual. Thus the probability of colliding more than three molecules at the same time...
Oxygen is available in plenty in the air yet fuels do not burn by themselves at room temperature. Explain.
Oxygen is found in the air but fuels do not burn themselves at room temperature because reactants must have a small amount of energy to form the products which is known as activation energy.
Why does the rate of a reaction increase with a rise in temperature?
The reaction rate increases with increasing temperature because at higher temperatures the friction of the colliding particles across the energy barrier will be larger. So the rate is also faster.
The reaction between H2(g) and O2(g) is highly feasible yet allowing the gases to stand at room temperature in the same vessel does not lead to the formation of water. Explain.
According to Maxwell Boltzmann's energy distribution curve, where the temperature T + 10 degree Celsius then the collision of molecular energy efficiency increases which leads to product formation....
For a general reaction A → B, plot of concentration of A vs time is given in Figure. Answer the following question based on this graph.
(i) What is the order of the reaction? (ii) What is the slope of the curve? (iii) What are the units of the rate constant? Answers: (i) Zero-order reaction is the order of reaction. (ii)...
For a zero-order reaction will the molecularity be equal to zero? Explain.
The molecularity of any reaction is the number of reactions involved in the basic reaction. Zero molecularity means that there is no reactant so reaction does not occur. Thus molecularity cannot be...
For a certain reaction large fraction of molecules has energy more than the threshold energy, yet the rate of reaction is very slow. Why?
The two most important responses that occur according to the collision theory are that the energy is greater than the activation energy and the correct position of the reactant molecules during a...
For a reaction A + B → Products, the rate law is — Rate = k [A][B]3/2 Can the reaction be an elementary reaction? Explain.
In an elementary reaction both the molecularity and order must be same. So, the given reaction is not an elementary reaction as the order of the given reaction is different.
Derive an expression to calculate the time required for completion of the zero-order reaction.
Let us take a reaction, R → P t=0 R = Reactant P = Product Rate = k[R]0 t=t –dR/dt = k , dR =-kdt Integrate on both the sides, ʃDr = -k ʃdt [R] = -kt + I If, t = 0 [R]= [R0] Then, I= R0 [R] = [R0]–...
In a reaction, if the concentration of reactant A is tripled, the rate of reaction becomes twenty-seven times. What is the order of the reaction?
Let us take the rate of a reaction, Rate = k[A]α Multiplying the rate into twenty seven, 27 ˟ Rate = k[A]α Dividing the equations, α = 3 Hence, Order of the reaction = 3
For which type of reactions, order and molecularity have the same value?
The type of reaction that have the same value of order and molecularity is the elementary reaction. This type of reaction happens in only one step.
How can you determine the rate law of the following reaction? 2NO (g) + O2 (g) → 2NO2 (g)
Rate law of a reaction can be determined by the formula, Rate = k[NO]2[O2]1 The rate law can be measured by the reaction rate as the initial concentration activity by keeping the concentration of...
Write the rate equation for the reaction 2A + B → C if the order of the reaction is zero.
Rate Equation of the reaction: k[A]0[B]0 The concentration capacity of the reactants will be equal to zero. In the zero-order reaction, the rate constant and rate of the reaction is the same....
State a condition under which a bimolecular reaction is a kinetically first-order reaction.
Condition: A situation in which the order of a chemical reaction can be converted under it by taking a solvent or reactant at an exorbitant rate because its concentration does not change much. Let...
In any unimolecular reaction ______________.
(i) only one reacting species is involved in the rate-determining step. (ii) the order and the molecularity of the slowest step are equal to one. (iii) the molecularity of the reaction is one and...
For a complex reaction ______________.
(i) order of an overall reaction is the same as molecularity of the slowest step. (ii) order of an overall reaction is less than the molecularity of the slowest step. (iii) order of an overall...
At high pressure, the following reaction is zero order. 2NH3(g) →1130 K Platinum catalyst N2(g) + 3H2(g)
Which of the following options are correct for this reaction? (i) Rate of reaction = Rate constant (ii) Rate of the reaction depends on the concentration of ammonia. (iii) Rate of decomposition of...
During decomposition of an activated complex.
(i) energy is always released (ii) energy is always absorbed (iii) energy does not change (iv) reactants may be formed Correct Answers: (i) energy is always released (iv) reactants may be...
According to Maxwell Boltzmann distribution of energy, __________.
(i) the fraction of molecules with most probable kinetic energy decreases at higher temperatures. (ii) the fraction of molecules with most probable kinetic energy increases at higher temperatures....
In the graph showing Maxwell Boltzman distribution of energy, ___________.
(i) the area under the curve must not change with an increase in temperature. (ii) the area under the curve increases with increase in temperature. (iii) the area under the curve decreases with...
Which of the following statements are in accordance with the Arrhenius equation?
(i) Rate of a reaction increases with increase in temperature. (ii) Rate of a reaction increases with a decrease in activation energy. (iii) Rate constant decreases exponentially with an increase in...
Mark the incorrect statements.
(i) Catalyst provides an alternative pathway to a reaction mechanism. (ii) Catalyst raises the activation energy. (iii) A catalyst lowers the activation energy. (iv) Catalyst alters enthalpy change...
Which of the following graphs is correct for a zero-order reaction?
Correct Answers: Option (ii) Option (iv) Explanation: The graphs (ii) and (iv) represents a proper zero-order reaction.
Which of the following graphs is correct for a first-order reaction?
Correct Answers: Option (i) Option (iv) Explanation: The graphs (i) and (iv) represents a proper first-order reaction.
Compounds ‘A’ and ‘B’ react according to the following chemical equation. A (g) + 2 B (g) → 2C (g)
The concentration of either ‘A’ or ‘B’ was changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration. Following results were...
Which of the following statement is not correct for the catalyst?
(i) It catalyses the forward and backward reaction to the same extent. (ii) It alters ∆G of the reaction. (iii) It is a substance that does not change the equilibrium constant of a reaction. (iv) It...
The value of rate constant of a pseudo first order reaction ____________.
(i) depends on the concentration of reactants present in a small amount. (ii) depends on the concentration of reactants present in excess. (iii) is independent of the concentration of reactants....
Consider the reaction A B. The concentration of both the reactants and the products varies exponentially with time. Which of the following figures correctly describes the change in concentration of reactants and products with time?
Correct Answer: Option (ii) Explanation: The graph in the option (ii) describes the change in concentration of reactants and products with time.
Rate law cannot be determined from the balanced chemical equation if _______.
(i) the reverse reaction is involved. (ii) it is an elementary reaction. (iii) it is a sequence of elementary reactions. (iv) any of the reactants is in excess Correct Answers: (i) the...
Which of the following statements apply to a balanced chemical equation of an elementary reaction?
(i) Order is the same as molecularity. (ii) Order is less than the molecularity. (iii) Order is greater than the molecularity. (iv) Molecularity can never be zero. Correct Answers: (i) Order...
A first-order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?
(i) 1.26 × 1015 s (ii) 2.52 × 1014 s (iii) 2.52 × 1028 s (iv) infinite Correct Answer: (iv) infinite Explanation: The time taken for the 100% completion of the reaction is...
Which of the following statements is incorrect about the collision theory of chemical reaction?
(i) It considers reacting molecules or atoms to be hard spheres and ignores their structural features. (ii) A number of effective collisions determine the rate of reaction. (iii) The collision of...
The rate law for the reaction A + 2B → C is found to be Rate = k [A][B]. The concentration of reactant ‘B’ is doubled, keeping the concentration of ‘A’ constant, the value of rate constant will be______.
(i) the same (ii) doubled (iii) quadrupled (iv) halved Correct Answer: (i) the same Explanation: For the given rate law of the reaction, if the concentration of reactant ‘B’ is doubled,...
Which of the following graph represents the exothermic reaction?
(i) (a) only (ii) (b) only (iii) (c) only (iv) (a) and (b) Correct Answer: (i) (a) only Explanation: The graph (a) represents the exothermic reaction.
Which of the following expressions is correct for the rate of reaction given below? 5Br–(aq) + BrO3–(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(l)
Correct Answer: Option (iii) Explanation: The third option shows the correct expression for the rate of the reaction.
Which of the following statements is correct?
(i) The rate of a reaction decreases over time as the concentration of reactants decreases. (ii) The rate of a reaction is the same at any time during the reaction. (iii) The rate of a reaction is...
Consider the graph given in Figure. Which of the following options does not show the instantaneous rate of reaction at 40th second?
(i) V5-V2/50-30 (ii) V4-V2/50-30 (iii) V3-V2/40-30 (iv) V3-V1/40-20 Correct Answer: (i) V5-V2/50-30 Explanation: V5-V2/50-30 do not show instantaneous rate of reaction at 40th...
Which of the following statements is not correct about an order of a reaction.
(i) The order of a reaction can be a fractional number. (ii) Order of a reaction is experimentally determined quantity. (iii) The order of a reaction is always equal to the sum of the stoichiometric...
A graph of volume of hydrogen released vs time for the reaction between zinc and dil.HCl is given in Figure. On the basis of this mark the correct option.
(i) Average rate up to 40s is V3-V2/40 (ii) Average rate up to 40s is V3-V2/40-30 (iii) Average rate up to 40 seconds is V3/40 (iv) Average rate up to 40 seconds is V3-V1/40-20 Correct...
Consider the Arrhenius equation given below and mark the correct option. a–E /RT k = A e
(i) Rate constant increases exponentially with increasing activation energy and decreasing temperature. (ii) Rate constant decreases exponentially with increasing activation energy and decreasing...
According to Arrhenius equation rate constant k is equal to A e–E /RT a. Which of the following options represents the graph of ln k vs 1/T
Correct Answer: Option (i) Explanation: According to Arrhenius equation, the graph represented in the first option is a straight line with negative slope.
Consider a first order gas phase decomposition reaction given: A(g) → B(g) + C(g)
The initial pressure of the system before decomposition of A was pi. After lapse of time ‘t’, total pressure of the system increased by x units and became ‘pt The rate constant k for the reaction is...
Consider the Figure and mark the correct option.
(i) The activation energy of forwarding reaction is E1 + E2 and the product is less stable than reactant. (ii) The activation energy of forwarding reaction is E1+E2and product is more stable than...
Activation energy of a chemical reaction can be determined by _____________.
(i) determining the rate constant at standard temperature. (ii) determining the rate constants at two temperatures. (iii) determining the probability of collision. (iv) using catalyst. ...
In the presence of a catalyst, the heat evolved or absorbed during the reaction ___________.
(i) increases. (ii) decreases. (iii) remains unchanged. (iv) may increase or decrease. Correct Answer: (iii) remains unchanged Explanation: The enthalpy change of the reaction will not be...
The role of a catalyst is to change ______________.
(i) gibbs energy of reaction. (ii) enthalpy of reaction. (iii) activation energy of reaction. (iv) equilibrium constant. Correct Answer: (iii) activation energy of reaction Explanation: The...
Consider the following diagram in which an electrochemical cell is coupled to an electrolytic cell. What will be the polarity of electrodes ‘A’ and ‘B’ in the electrolytic cell?
Zinc leaves behind the electrons on Electrode A during the reaction giving a negative charged whereas the Copper deposits on the Electrode B with positive charge. The polarity of electrode A...
Why is alternating current used for measuring the resistance of an electrolytic solution?
The concentration of ions is kept constant with the alternating current whereas the concentration of ion changes a lot in the direct current. So, the alternating current is used for measuring the...
A galvanic cell has an electrical potential of 1.1V. If an opposing potential of 1.1V is applied to this cell, what will happen to the cell reaction and current flowing through the cell?
If the opposing potential is equal to electrical potential, then the cell reaction and the current flow through the cell will be stopped leading to no chemical reaction.
How will the pH of brine (aq. NaCl solution) be affected when it is electrolyzed?
Reaction on Cathode - H2O(l ) + e–→ 1/2 H2(g) + OH– (aq) Reaction on Anode - Cl– (aq) → 1/2 Cl2(g) + e– Complete Reaction: NaCl(aq)+H2O(l)→NaOH(aq)+H2(g)+Cl2(g) NaOH turns the brine solution basic...
Unlike dry cell, the mercury cell has a constant cell potential throughout its useful life. Why?
The electrolyte is not consumed in the cell and so the current gets delivered at a constant potential till the end. The reaction contains no ions whose concentration can change over time. Thus, the...
Solutions of two electrolytes ‘A’ and ‘B are diluted. The of ‘B’ increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Justify your answer.
Electrolyte B - strong electrolyte During dilution the number of ions remains the same and the interionic attraction decreases. Thus, the increase in Λm is small.
When acidulated water (dil.H2SO4 solution) is electrolysed, will the pH of the solution be affected? Justify your answer.
Reaction on Anode - 2H2O(l)→ O2(g) + 4H+ (aq) + 4e– Reaction on Cathode - 4H+ + 4e-→ 2H2 Complete Reaction: 2H2O(l) → O2(g) + 2H2(g) The pH will not be affected and stays the same.
In an aqueous solution, how does specific conductivity of electrolytes change with the addition of water?
In an aqueous solution, when water is added the electrolyte gets diluted thus leading to the decrease in the specific conductivity of the electrolytes.
Which reference electrode is used to measure the electrode potential of other electrodes?
The reference electrode which is used to measure the electrode potential of other electrodes is the Standard hydrogen electrode (SHE) which has a value of zero.
Consider a cell given: Cu|Cu2+|| Cl—|Cl2, Pt Write the reactions that occur at anode and cathode.
Reaction in Anode: Oxidation half-cell Cu(s) → Cu2+ + 2e- Reaction in Cathode: Reduction half-cell Cl2(g)+ 2e-→ 2Cl- Hence, the anode Cu gets oxidised in this cell reaction.
Write the Nernst equation for the cell reaction in the Daniel cell. How will the ECell be affected when the concentration of Zn2+ ions is increased?
Nernst Equation: Ecell = E°cell – RT[Zn2+]/ nF[Cu2+] Galvanic cell reaction: Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s) Reaction in Anode: oxidation half-cell Zn(s) → Zn2+ (aq)+ 2e Reaction in Cathode:...
What advantage do the fuel cells have over primary and secondary batteries?
Advantages of Fuel cells: 1.Fuel cells can convert the energy of combustion of fuels like hydrogen, methanol into electrical energy. 2.Fuel cells can run continuously as long as reactants are...
Write the cell reaction of a lead storage battery when it is discharged. How does the density of the electrolyte change when the battery is discharged?
While discharging the battery, the water dilutes the concentration of the dilute sulphuric acid which leads to a decrease in the density of the solution. Reaction Involved: Pb(s)+PbO2(s)+2H2SO4(aq)→...
Why on dilution the ˄m of CH3COOH increases drastically, while that of CH3COONa increases gradually?
Weak Electrolyte: CH3COOH Strong Electrolyte: CH3COONa . When diluted, the dissociation degree increases, and the number of ions present also increases which leads to the drastic increase of CH3COOH...
What is electrode potential?
Electrode potential is the potential difference which is developed between the electrode and the electrolyte.
Value of standard electrode potential for the oxidation of Cl– ions is more positive than that of water, even then in the electrolysis of aqueous sodium chloride, why is Cl–oxidised at anode instead of water?
The oxidation of water to oxygen is kinetically not good and requires a lot of energy which is said to have more energy. What can be very powerful is the excess energy needed to drive the reaction...
Aqueous copper sulphate solution and aqueous silver nitrate solution are electrolysed by 1 ampere current for 10 minutes in separate electrolytic cells. Will, the mass of copper and silver, deposited on the cathode be the same or different? Explain your answer.
W = itE/96500 W = 1×10×60×31.75/96500 Equivalent mass of Cu2+ and Ag+ is different so that the mass of copper and silver deposited will not be same.
What does the negative sign in the expression E°Zn2+/Zn = -0.76V mean?
The disadvantage is that hydrogen gas is much more stable than reduced species. Here, the reduced form (Zn) is unstable. It is difficult to reduce Zn2 + to Zn. Therefore, distortion is more likely...
Under what condition is ECell = 0 or ΔrG = 0?
Electrolysis happens when a redox reaction happens. On equilibrium, the cell is completely depleted, and the cell's energy drops to zero. ∆rG= -nF E cell =0
Can E°cell or ΔrG° for cell reaction ever be equal to zero?
A cell of E ° or G G ° cannot be equal to zero. The only standard electrode power is randomly assigned is the standard hydrogen electrode (SHE). As everything else is measured in relation to SHE;...
Can absolute electrode potential of an electrode be measured?
No. It cannot be measured. We can only estimate the electrode power difference between two and a half cells. We can also estimate the potential electrode differences associated with a standard...
For the given cell, Mg|Mg2+|| Cu2+|Cu
(i) Mg is cathode (ii) Cu is cathode (iii) The cell reaction is Mg + Cu2+ → Mg2+ + Cu (iv) Cu is the oxidising agent Correct Answers: (ii) Cu is cathode (iii) The cell reaction is Mg + Cu2+ →...
Molar conductivity of ionic solution depends on ___________.
(i) temperature. (ii) distance between electrodes. (iii) the concentration of electrolytes in solution. (iv) the surface area of electrodes. Correct Answers: (i) temperature. (iii) the...
Conductivity κ , is equal to ____________.
(i) 1/R l/A (ii) G*/R (iii) ˄m (iv) l/A Correct Answers: (i) 1/R l/A (ii) G*/R Explanation: Conductivity κ , is equal to 1/R l/A & G*/R
What will happen during the electrolysis of an aqueous solution of CuSO4 in the presence of Cu electrodes?
(i) Copper will deposit at the cathode. (ii) Copper will dissolve at the anode. (iii) Oxygen will be released at anode. (iv) Copper will deposit at the anode. Correct Answers: (i) Copper will...
What will happen during the electrolysis of an aqueous solution of CuSO4 by using platinum electrodes?
(i) Copper will deposit at the cathode. (ii) Copper will deposit at the anode. (iii) Oxygen will be released at anode. (iv) Copper will dissolve at the anode Correct Answers: (i) Copper will...
˄0m(H2O) is equal to ______________.
(i) ˄0m(HCl) + ˄0m(NaOHl) – ˄0m(NaCl) (ii) ˄0m(HNO3) + ˄0m(NaNO3) – ˄0m(NaOH) (iii) ˄0m(HNO3) + ˄0m(NaOH) – ˄0m(NaNO3) (iv) ˄0m(NH4OH) + ˄0m(HCl) – ˄0m(NH4Cl) Correct Answers: (i) ˄0m(HCl) +...
Conductivity of an electrolytic solution depends on ____________.
(i) nature of electrolyte. (ii) the concentration of electrolyte. (iii) power of AC source. (iv) distance between the electrodes. Correct Answers: (i) nature of electrolyte. (ii) the...
E°Cell = 1.1V for Daniel cell. Which of the following expressions are correct description of state of equilibrium in ths cell?
(i) 1.1 = Kc (ii) 2.303RT/2F logKc = 1.1 (iii) log Kc = 2.2/0.059 (iv) log Kc = 1.1 Correct Answers: (ii) 2.303RT/2F logKc = 1.1 (iii) log Kc = 2.2/0.059
E°Cell for some half cell reactions are given below. Based on these mark the correct answer.
(a) H+(aq) + e– →1/2H2(g) ; E°cell = 0.00V (b) 2H2O (l) → O2 (g) + 4H+(aq) + 4e–: E°cell = 1.23V (c) 2SO42– (aq) → S2O82– (aq) + 2e– ; E°cell = 1.96V (i) In dilute sulphuric acid solution, hydrogen...
The positive value of the standard electrode potential of Cu2+/Cu indicates that ____________.
(i) this redox couple is a stronger reducing agent than the H+/H2 couple. (ii) this redox couple is a stronger oxidising agent than H+/H2. (iii) Cu can displace H2 from acid. (iv) Cu cannot displace...
In the electrolysis of aqueous sodium chloride solution which of the half cell reaction will occur at anode?
(i) Na+(aq) + e– → Na (s); E°Cell = –2.71V (ii) 2H2O (l) → O2(g) + 4H+(aq) + 4e– : E°Cell = 1.23V (iii) H+(aq) + e–→1/2H2 (g); E°Cell = 0.00V (iv) Cl–(aq) →1/2Cl2(g) + e– ; E°Cell = 1.36V ...
˄0m(NH4OH) is equal to ______________.
(i) ˄0m(NH4OH) + ˄0m(NH4Cl) – ˄0(HCl) (ii) ˄0m(NH4Cl) + ˄0m(NaOH) – ˄0(NaCl) (iii) ˄0m(NH4Cl) + ˄0m(NaCl) – ˄0(NaOH) (iv) ˄0m(NaOH) + ˄0m(NaCl) – ˄0(NH4Cl) Correct Answer: (ii) ˄0m(NH4Cl) +...
While charging the lead storage battery ______________.
(i) PbSO4 anode is reduced to Pb (ii) PbSO4 cathode is reduced to Pb (iii) PbSO4 cathode is oxidised to Pb (iv) PbSO4 anode is oxidised to PbO2 Correct Answer: (i) PbSO4 anode is reduced to...
The cell constant of a conductivity cell _____________.
(i) changes with the change of electrolyte. (ii) changes with the change of concentration of electrolyte. (iii) changes with the temperature of the electrolyte. (iv) remains constant for a cell....
The quantity of charge required to obtain one mole of aluminium from Al2O3 is ___________.
(i) 1F (ii) 6F (iii) 3F (iv) 2F Correct Answer: (iii) 3F Explanation: 3F of charge is required to obtain 1 mole of Al from the Al2O3
Use the data of Q.8 and find out the most stable oxidised species.
(i) Cr3+ (ii) MnO4– (iii) Cr2O72– (iv) Mn2+ Correct Answer: (i) Cr3+ Explanation: Cr3+ is the most stable oxidised species when compared to the rest of the options.
Use the data given in Q.8 and find out the most stable ion in its reduced form.
(i) Cl– (ii) Cr3+ (iii) Cr (iv) Mn2+ Correct Answer: (iv) Mn2+ Explanation: Mn2+ in its reduced form is observed to be more stable.
Using the data given in Q.8 find out in which option the order of reducing power is correct.
(i) Cr3+ < Cl–< Mn2+ < Cr (ii) Mn2+ < Cl–< Cr3+ < Cr (iii) Cr3+ < Cl–< Cr2O72– < MnO4– (iv) Mn2+ < Cr3+ < Cl–< Cr Correct Answer: (ii) Mn2+ < Cl–<...
Use the data given in Q.8 and find out which of the following is the strongest oxidising agent.
(i) Cl– (ii) Mn2+ (iii) MnO4– (iv) Cr3+ Correct Answer: (iii) MnO4– Explanation: The higher the value of the normal reduction of the strength of the metal ion, the higher will be its...
Using the data given below to find out the strongest reducing agent.
EᶱCr2O72-/Cr3+ = 1.33V EᶱMnO4–/Mn2+ = 1.51V EᶱCl2/Cl– = 1.36V EᶱCr3+/Cr = -0.74V (i) Cl– (ii) Cr (iii) Cr3+ (iv) Mn Correct Answer: (ii) Cr Explanation: The most powerful reducing agent is...
Which of the statements about solutions of electrolytes is not correct?
(i) The conductivity of the solution depends upon the size of ions. (ii) Conductivity depends upon the viscosity of the solution. (iii) Conductivity does not depend upon solvation of ions present in...
An electrochemical cell can behave like an electrolytic cell when ____________.
(i) Ecell = 0 (ii) Ecell > Eext (iii) Eext > Ecell (iv) Ecell = Eext Correct Answer: (iii) Eext > Ecell
Which of the following statement is not correct about an inert electrode in a cell?
(i) It does not participate in the cell reaction. (ii) It provides surface either for oxidation or for the reduction reaction. (iii) It provides a surface for conduction of electrons. (iv) It...
The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called ___________.
(i) Cell potential (ii) Cell emf (iii) Potential difference (iv) Cell voltage Correct Answer: (ii) Cell emf Explanation: Electromotive force or e.m.f. is the power provided by the cell or...
Which of the following statement is correct?
(i) ECell and ∆rG of cell reaction both are extensive properties. (ii) ECell and ∆rG of cell reaction both are intensive properties. (iii) ECell is an intensive property while ∆rG of cell reaction...
Electrode potential for Mg electrode varies according to the equation EMg2+/Mg = EᶱMg2+/Mg – 0.0591/2 log1/[Mg2+ ] . The graph of EMg2+/Mg Vs log [Mg2+] is
Correct Answer: Option (ii)
Which cell will measure standard electrode potential of copper electrode?
(i) Pt (s) H2(g,0.1 bar) H+ (aq.,1 M) Cu2+(aq.,1M) Cu (ii) Pt(s) H2 (g, 1 bar) H+ (aq.,1 M) Cu2+ (aq.,2 M) Cu (iii) Pt(s) H2(g, 1 bar) H+ (aq.,1 M) Cu2+ (aq.,1 M) Cu (iv) Pt(s) H2 (g, 1 bar)...
Match the terms given in Column I with expressions given in Column II.
Column I Column II (i) Mass percentage (a)Number of moles of the solute component/ The volume of solution in litres (ii) Volume percentage (b) Number of moles of a component/...
Match the laws given in Column I with expressions given in Column II.
Column I Column II (i) Raoult’s law (a) ∆Tf= Kfm (ii) Henry’s law (b) Π = CRT (iii) Elevation of boiling point (c) p = x1P10+ X2P20 (iv) Depression in freezing point (d) ∆Tb= Kbm (v) Osmotic...
Match the items given in Column I with the type of solutions given in Column II.
Column I Column II (i) Soda water (a) A solution of the gas in solid (ii) Sugar solution (b) A solution of the gas in gas (iii) German silver (c) A solution of...
Match the items given in Column I and Column II.
Column I Column II (i) Saturated solution (a) Solution having the same osmotic pressure at a given temperature as that of the given solution. (ii) Binary solution (b) A solution whose...
Give an example of a material used for making semipermeable membrane for carrying out reverse osmosis.
Examples: Cellulose acetate Polyamides
What is a “semi-permeable membrane”?
Semi-permeable membrane is a membrane that allows only the movement of solvent molecules but not solute molecules. Examples: Cellulose acetate and phospholipid bilayer in biological cells.
How does sprinkling of salt help in clearing the snow-covered roads in hilly areas? Explain the phenomenon involved in the process.
Salt is an agent for de-icing and can be used to dissolve ice. If the freezing point is lowered the ice begins to melt. Thus, the addition of salt to ice reduces the freezing point from O ℃ drop.
Why is the vapour pressure of an aqueous solution of glucose lower than that of water?
An example of water and glucose can be taken to illustrate this. In water, the surface of this liquid will settle with water molecules. If we put glucose into it, some of these areas will be...
On the basis of information given mark the correct option. Information: On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.
(i) At specific composition, methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult’s law. (ii) At specific composition, methanol-acetone mixture...
(a) Explain the following phenomena with the help of Henry’s law. (i) A painful condition known as bends. (ii) Feeling of weakness and discomfort in breathing at high altitude. (b) Why soda water bottle kept at room temperature fizzes on opening?
(a) (i) The bend is a condition that occurs in scuba divers. They have to breathe air under high pressure under water. Nitrogen gas does not dissolve in normal pressure. Under water, they will...
Why are aquatic species more comfortable in cold water in comparison to warm water?
Because of the availability of O2 and the presence of more solubility in the cold water makes the aquatic species feel more comfortable when present in the cold water.
What is the significance of Henry’s Law constant KH?
Significance of Henry’s Law constant KH: Henry's law states that in the solution, "the pressure in the gas component at the vapor fraction (p) is equal to the fraction of the gas molecule (x) in...
Concentration terms such as mass percentage, ppm, mole fraction and molality are independent of temperature, however, molarity is a function of temperature. Explain.
Any change in the temperature causes a change in the volume, so it changes the molarity of the solution. Therefore, terms such as high percentage, ppm, mole fraction, and molality of a solution are...
Explain the solubility rule “like dissolves like” in terms of intermolecular forces that exist in solutions.
"Like dissolves like" term is used when the solvent dissolves in the solvent if its interactions between molecules are the same. This is because polar solutions can be dissolved in polar solvents...
Explain why on the addition of 1 mol of NaCl to 1 litre of water, the boiling point of water increases, while the addition of 1 mol of methyl alcohol to one litre of water decreases its boiling point.
Adding 1 mol of NaCl to 1 liter of water, a point of boiling water rises, while the addition of 1 mol of methyl alcohol to one liter of water reduces its boiling point because when added to a stable...
Components of a binary mixture of two liquids A and B were being separated by distillation. After some time separation of components stopped and the composition of the vapour phase became the same as that of a liquid phase. Both the components started coming in the distillate. Explain why this happened.
An azeotropic mixture is shown when both the liquids A & B starts coming in the distillate and the vapour and liquid phase will have the same composition. Via distillation an azeotropic mixture...
Colligative properties are observed when _____________.
(i) a non-volatile solid is dissolved in a volatile liquid. (ii) a non-volatile liquid is dissolved in another volatile liquid. (iii) a gas is dissolved in non-volatile liquid. (iv) a volatile...
For a binary ideal liquid solution, the variation in total vapour pressure versus the composition of the solution is given by which of the curves?
Correct Answers: Option (ii) Option (iv) Explanation: For the binary solution, the difference in vapor pressure versus the composition of the solution is given in graphs B and D where, the...
In isotonic solutions ________________.
(i) solute and solvent both are same. (ii) osmotic pressure is the same. (iii) solute and solvent may or may not be same. (iv) a solute is always the same solvent may be different. Correct...
Which of the following binary mixtures will have the same composition in the liquid and vapour phase?
(i) Benzene – Toluene (ii) Water-Nitric acid (iii) Water-Ethanol (iv) n-Hexane – n-Heptane Correct Answers: (ii) Water-Nitric acid (iii) Water-Ethanol Explanation: In a particular...
Isotonic solutions must have the same _____________.
(i) solute (ii) density (iii) elevation in boiling point (iv) depression in freezing point Correct Answers: (iii) elevation in boiling point (iv) depression in freezing point Explanation:...
Van’t Hoff factor is given by the expression _____________.
(i) i = Normal molar mass/Abnormal molar mass (ii) i = Abnormal molar mass/ Normal molar mass (iii) i= Observed colligative property/calculated colligative property (iv) i = Calculated colligative...
Relative lowering of vapour pressure is a colligative property because _____________.
(i) It depends on the concentration of a non-electrolyte solute in a solution and does not depend on the nature of the solute molecules. (ii) It depends on a number of particles of electrolyte...
Intermolecular forces between two benzene molecules are near to same strength as those between two toluene molecules. For a mixture of benzene and toluene, which of the following are not true?
(i) ∆mix H = zero (ii) ∆mix V = zero (iii) These will form a minimum boiling azeotrope. (iv) These will not form the ideal solution. Correct Answers: (iii) These will form a minimum boiling...
Which of the following factor (s) affect the solubility of a gaseous solute in a fixed volume of liquid solvent? (a) nature of solute (b) temperature (c) pressure
(i) (a) and (c) at constant T (ii) (a) and (b) at constant P (iii) (b) and (c) only (iv) (c) only Correct Answers: (i) (a) and (c) at constant T (ii) (a) and (b) at constant P Explanation: At...
KH value for Ar(g), CO2(g), HCHO (g) and CH4(g) are 40.39, 1.67, 1.83×10–5 and 0.413 respectively. Arrange these gases in the order of their increasing solubility.
(i) HCHO < CH4< CO2 < Ar (ii) HCHO < CO2< CH4< Ar (iii) Ar < CO2< CH4< HCHO (iv) Ar < CH4 < CO2 < HCHO Correct Answer: (iii) Ar < CO2< CH4< HCHO...
4L of 0.02 M aqueous solution of NaCl was diluted by adding one litre of water. The molality of the resultant solution is _____________.
(i) 0.004 (ii) 0.008 (iii) 0.012 (iv) 0.016 Correct Answer: (iv) 0.016 Explanation: Let us take, M1 and V1 - molarity and volume of the given solution. M2 and V2 - molarity and volume of...
If two liquids A and B form minimum boiling azeotrope at some specific composition then _______________.
(i) A–B interactions are stronger than those between A–A or B–B. (ii) vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution. (iii)...
Two beakers of capacity 500 mL were taken. One of these beakers, labeled as “A”, was filled with 400 mL water whereas the beaker labelled “B” was filled with 400 mL of 2 M solution of NaCl. At the same temperature, both the beakers were placed in closed containers of the same material and same capacity as shown in Figure. At a given temperature, which of the following statement is correct about the vapour pressure of pure water and that of NaCl solution.
(i) the vapour pressure in container (A) is more than that in a container (B). (ii) the vapour pressure in container (A) is less than that in the container (B). (iii) vapour pressure is equal in...
On the basis of information given below mark the correct option. Information:
(A) In bromoethane and chloroethane mixture intermolecular interactions of A–A and B–B type are nearly the same as A–B type interactions. (B) In ethanol and acetone mixture A–A or B–B type...
We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van’t Hoff factor for these solutions will be in the order______.
(i) iA< iB< iC (ii) iA> iB> iC (iii) iA= iB= iC (iv) iA<iB> iC Correct Answer: (iii) iA= iB= iC
Consider the Figure and mark the correct option.
(i) water will move from the side (A) to side (B) if a pressure lower than the osmotic pressure is applied on piston (B). (ii) water will move from the side (B) to side (A) if a pressure greater...
The value of Henry’s constant KH is _____________.
(i) greater for gases with higher solubility. (ii) greater for gases with lower solubility. (iii) constant for all gases. (iv) not related to the solubility of gases Correct Answer: (ii)...
Value of Henry’s constant KH ____________.
(i) increases with increase in temperature. (ii) decreases with increase in temperature. (iii) remains constant. (iv) first increases then decrease. Correct Answer: (i) increases with...
Which of the following statements is false?
(i) Units of atmospheric pressure and osmotic pressure are the same. (ii) In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute...
The values of Van’t Hoff factors for KCl, NaCl and K2SO4, respectively, are _____________.
(i) 2, 2 and 2 (ii) 2, 2 and 3 (iii) 1, 1 and 2 (iv) 1, 1 and 1 Correct Answer: (ii) 2, 2 and 3 Explanation: The values of van't Hoff factors for KCl,...
Which of the following statements is false?
(i) Two different solutions of sucrose of the same molality prepared in different solvents will have the same depression in freezing point. (ii) The osmotic pressure of a solution is given by the...
At a given temperature, osmotic pressure of a concentrated solution of a substance _____________.
(i) is higher than that at a dilute solution. (ii) is lower than that of a dilute solution. (iii) is same as that of a dilute solution. (iv) cannot be compared with an osmotic pressure of a dilute...
An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because _____________.
(i) it gains water due to osmosis. (ii) it loses water due to reverse osmosis. (iii) it gains water due to reverse osmosis. (iv) it loses water due to osmosis. Correct Answer: (iv) it loses...
In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2 solution is _____________.
(i) the same (ii) about twice (iii) about three times (iv) about six times Correct Answer: (iii) about three times Explanation: The depression in freezing point of a 0.01M MgCl2 solution is...
The unit of ebulioscopic constant is _______________.
(i) K kg mol-1 or K (molality)-1 (ii) mol kg K-1 or K-1(molality) (iii) kg mol-1 K-1 or K-1(molality)-1 (iv) K mol kg-1 or K (molality) Correct Answer: (i) K kg mol-1 or K (molality)-1...
Which of the following aqueous solutions should have the highest boiling point?
(i) 1.0 M NaOH (ii) 1.0 M Na2SO4 (iii) 1.0 M NH4NO3 (iv) 1.0 M KNO3 Correct Answer: (ii) 1.0 M Na2SO4 Explanation: Given that a large amount of van's Hoff will increase the boiling point of...
Colligative properties depend on ____________.
(i) the nature of the solute particles dissolved in solution. (ii) the number of solute particles in solution. (iii) the physical properties of the solute particles dissolved in solution. (iv) the...
Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
(i) Methanol and acetone. (ii) Chloroform and acetone. (iii) Nitric acid and water. (iv) Phenol and aniline. Correct Answer: (i) Methanol and acetone Explanation: The mixture of methanol and...
Low concentration of oxygen in the blood and tissues of people living at high altitude is due to ____________.
(i) low temperature (ii) low atmospheric pressure (iii) high atmospheric pressure (iv) both low temperature and high atmospheric pressure Correct Answer: (ii) low atmospheric pressure...
The maximum amount of a solid solute that can be dissolved in a specified amount of a given liquid solvent does not depend upon ____________.
(i) Temperature (ii) Nature of solute (iii) Pressure (iv) Nature of solvent Correct Answer: (iii) Pressure Explanation: Changes in pressure do not affect the solubility of solids and the...
A beaker contains a solution of a substance ‘A’. Precipitation of substance ‘A’ takes place when a small amount of ‘A’ is added to the solution. The solution is _________.
(i) saturated (ii) supersaturated (iii) unsaturated (iv) concentrated Correct Answer: (ii) supersaturated Explanation: Most of the substance does not dissolve when we add more solute will not...
At equilibrium the rate of dissolution of a solid solute in a volatile liquid solvent is __________.
(i) less than the rate of crystallisation (ii) greater than the rate of crystallisation (iii) equal to the rate of crystallisation (iv) zero Correct Answer: (iii) equal to the rate of...
On dissolving sugar in water at room temperature solution feels cool to touch. Under which of the following cases dissolution of sugar will be most rapid?
(i) Sugar crystals in cold water. (ii) Sugar crystals in hot water. (iii) Powdered sugar in cold water. (iv) Powdered sugar in hot water. Correct Answer: (iv) Powdered sugar in hot water...
Which of the following units is useful in relating the concentration of a solution with its vapour pressure?
(i) mole fraction (ii) parts per million (iii) mass percentage (iv) molality Correct Answer: (i) mole fraction Explanation: According to Raoult's law, the reduction associated with vapor...
How might you clarify the higher soundness of BCl3 when contrasted with TlCl3?
Solution: Thallium and boron have a place with bunch 13 of the intermittent table and +1 oxidation state turns out to be more steady as we drop down the gathering. Boron is more steady than thallium...
Which of the following statements are true about metals?
(i) Valence band overlaps with conduction band. (ii) The gap between the valence band and the conduction band is negligible. (iii) The gap between the valence band and the conduction band cannot be...
Under the influence of the electric field, which of the following statements is true about the movement of electrons and holes in a p-type semiconductor?
(i) The electron will move towards the positively charged plate through electron holes. (ii) Holes will appear to be moving towards the negatively charged plate. (iii) Both electrons and holes...
Which of the following statements are true about semiconductors?
(i) Silicon doped with an electron-rich impurity is a p-type semiconductor. (ii) Silicon doped with an electron-rich impurity is an n-type semiconductor. (iii) Delocalised electrons increase the...
An excess of potassium ions makes KCl crystals appear violet or lilac in colour since ________.
(i) some of the anionic sites are occupied by an unpaired electron. (ii) some of the anionic sites are occupied by a pair of electrons. (iii) there are vacancies at some anionic sites. (iv)...
The number of tetrahedral voids per unit cell in NaCl crystal is ________.
(i) 4 (ii) 8 (iii) twice the number of octahedral voids. (iv) four times the number of octahedral voids. Correct Answers: (ii) 8 (iii) twice the number of octahedral voids....
Amorphous solid can also be called ________.
(i) pseudo solids (ii) true solids (iii) supercooled liquids (iv) supercooled solids Correct Answers: (i) pseudo solids (iii) supercooled liquids Explanation: The formation of...
A perfect crystal of silicon is doped with some elements as given in the options. Which of these options show n-type semiconductors?
Correct Answers: Option (i) Option (iii) Explanation: N-type semiconductors are prepared by inserting a complete silicon crystal (Si) with pentavalent elements of group 15 like P and As. Some...
Which of the following statements are correct?
(i) Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic. (ii) Ferrimagnetic substances do not lose ferrimagnetism on heating and remain ferrimagnetic. (iii)...
Which of the following features are not shown by quartz glass?
(i) This is a crystalline solid. (ii) Refractive index is the same in all the directions. (iii) This has a definite heat of fusion. (iv) This is also called supercooled liquid. Correct...
Which of the following cannot be regarded as molecular solid?
(i) SiC (Silicon carbide) (ii) AlN (iii) Diamond (iv) I2 Correct Answers: (i) SiC (Silicon carbide) (ii) AlN (iii) Diamond Explanation: SiC, AIN and Diamond have three-dimensional...
In which of the following arrangements octahedral voids are formed?
(i) hcp (ii) bcc (iii) simple cubic (iv) fcc Correct Answers: (i) hcp (iv) fcc Explanation: In hep and fcc arrangement, octahedral voids are formed. Charging, octahedral voids are...
Frenkel defect is also known as ________.
(i) stoichiometric defect (ii) dislocation defect (iii) impurity defect (iv) non-stoichiometric defect Correct Answers: (i) stoichiometric defect (ii) dislocation defect Explanation:...
Which of the following defects decrease the density?
(i) Interstitial defect (ii) Vacancy defect (iii) Frankel defect (iv) Schottky defect Correct Answers: (ii) Vacancy defect (iv) Schottky defect Explanation: The Schottky and vacancy...
Why are liquids and gases categorised as fluids?
Liquids and gases can flow, and the molecules present in these two can move fast from one to another and therefore both the liquids and gases are separated as fluids.
Despite long-range order in the arrangement of particles why are the crystals usually not perfect?
The crystallization process will speed up so that the particles do not get enough time to set in perfect order. Therefore, crystals have a long particle structure but are incomplete.