The correct answer is a) number of charge carriers can change with temperature T b) time interval between two successive collisions can depend on T
Temperature dependence of resistivity ρ(T) of semiconductors, insulators, and metals is significantly based on the following factors:
An element X belongs to group 2 and another element Y belongs to group 15 of the periodic table: (a) What is the number of valence electrons in X? (b) What is the valency of X? (c) What the number of valence electrons in Y? (d) What is the valency of Y? Explain how you have arrived at your answers.
(a) 2. For the group 1 and 2, the number of valence electrons is equal to the group number and in the 2nd group, it is equal to 2. (b) 2. Valency is determined by the number of valence electrons...
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table. Write the electronic configurations of these two elements. Which of these will be more electronegative? Why?
The electronic configuration of nitrogen and phosphorous are as follows: N = (2,5) ; P = (2, 8, 5) Nitrogen will have more electronegativity because its atom has small size due to which the...
Fill in the blanks in the following statements: (a) The horizontal rows in a periodic table are called _______. (b) In going across a period (right to left) in periodic table, the atomic size of the atom _______. (c) On moving from right to left in the second period, the number of valence electrons _______. (d) On going down in a group in the periodic table, the metallic character of elements _______. (e) The tendency to gain an electron_______ on moving down in a group of the periodic table.
(a) Periods (b) Increases (c) Decreases (d) Increases (e) Decreases
Rewrite the following statements after correction, if necessary: (i) Elements in the same period have equal valency. (ii) The metallic character of elements in a period increases gradually on moving from left to right.
(i) Elements in the same group have equal valency. (ii)The metallic character of elements in a period decreases gradually on moving from left to right.
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
In the Modern Periodic Table, the element calcium has an atomic number 20, so it has 2, 8, 8, 2 electronic configurations. Therefore, this two valance electron containing element is identical to the...
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
In the Modern Periodic Table, the electronic configuration of an element determines the number of valence electrons whereas the position of the atom is determined by the valence electrons.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
Nitrogen: Atomic number - 7 Electronic configuration - 1s2 2s2 2p3 Nitrogen: Atomic number - 15 Electronic configuration - 1s2 2s2 2p6 3s2 3p3 The number of shell increases in the periodic table...
The position of three elements A, B and C in the Periodic Table are shown below–
Group 16 Group 17 - - - A - - B C (a) State whether A is a metal or non-metal. (b) State whether C is more reactive or less reactive than A. (c) Will C be larger or smaller in size than B?...
An atom has electronic configuration 2, 8, 7. (a) What is the atomic number of this element? (b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) N(7), F(9), P(15), Ar(18)
(a)The element is Chlorine (Cl) and the atomic number of chlorine is 17. (b) The atom with the electronic configuration of 2, 8, 7 which is the chlorine is chemically identical to Fluorine (F) which...
(a) What property do all elements in the same column of the Periodic Table as boron have in common? (b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
(a) All the elements are in the same boron column (group 13). Thus, they have three electrons in their valence shells. Besides, non-metallic boron, all other elements (i.e., aluminum, gallium,...
Which element has? (a) Two shells, both of which are completely filled with electrons? (b) The electronic configuration 2, 8, 2? (c) A total of three shells, with four electrons in its valence shell? (d) A total of two shells, with three electrons in its valence shell?(e) twice as many electrons in its second shell as in its first shell?
(a) Neon (Ne) has two shells in which both are completely filled with electrons. (b) Magnesium (Mg) has the electronic configuration 2, 8, 2. (c) Silicon (Si) has a total of three shells, with four...
Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as (a) Na (b) Mg (c) AI (d) Si
Identification: Element X - Magnesium (Mg) containing valency of 2. Explanation: When Mg is combined with chloride (Cl), it forms Magnesium Chloride (MgCl2).
Which of the following statements is not a correct statement about the trends when going from left to right across the periods of Periodic Table. (a) The elements become less metallic in nature. (b) The number of valence electrons increases. (c) The atoms lose their electrons more easily. (d) The oxides become more acidic
Correct Answer: (c) The atoms lose their electrons more easily Explanation: Atoms do not lose their electrons easily because as we move from left to right across the periodic table, the non-metallic...
By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic? Ga/Ge/As/Se/Be
The elements that are expected to have the most metallic character are Be and Ga. The tendency to lose electrons is greater in Ga than the Be as the size of Ga is bigger. Thus, the element Ga have...
In the Modern Periodic Table, which are the metals among the first ten elements?
The metals among the first ten elements in the modern periodic table are, Lithium Beryllium
(a) Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements? (b) Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?
(a) Lithium, sodium, potassium are the metals that are unstable because of the unfilled outermost shells. This is the reason that they react with water in order to release hydrogen and these metals...
Name 1. Three elements that have a single electron in their outermost shells. 2. Two elements that have two electrons in their outermost shells. 3. Three elements with filled outermost shells
Lithium (Li), Sodium (Na) and potassium (k) are the three elements that have only one electron in their outermost shells. Magnesium (Mg) and Calcium (Ca) are the two elements that contains...
Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
I think that the elements Calcium and Beryllium are expected to show chemical reactions that are similar to the element magnesium as these elements belong to the same group having 2 valence...
How could the Modern Periodic Table remove various anomalies of Mendeleev’s Periodic Table?
The Modern periodic table is arranged in order of their atomic number. This removes inconsistencies in relation to certain pairs of the elements present in the Mendeleev’s periodic table. The atomic...
Why do you think the noble gases are placed in a separate group?
The noble gases have been classified as separate group because of their inert nature as they are also called as inert gases. Noble gases are present in low concentration in our atmosphere. They are...
What were the criteria used by Mendeleev in creating his Periodic Table?
Mendeleev focused on a variety of chemicals made up of elements containing Hydrogen and Oxygen. Among the material, he saw the interrelationships between the mass of many atoms of various elements...
Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (Any two)
The elements that are left by the Mendeleev’s Periodic Table besides gallium are, Germanium Scandium
Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements: K, C, AI, Si, Ba.
According to the Mendeleev’s Periodic Table, Potassium (K) belongs to group IA with a valency of 1. Formula - K2O Carbon (C) belongs to group IV A with a valency of 4. Formula - C2O4 or CO2 Aluminum...
What were the limitations of Newlands’ Law of Octaves?
Limitations of Newlands’ Law of Octaves: Newlands Octave law applies only to the elements till Calcium. Newland estimates that there are a total of 56 elements in nature and that there are no more...
Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.
Mendeleev’s Periodic Table Modern Periodic Table In the Mendeleev’s Periodic Table, the arrangement of the elements are according to the increasing order of the element’s atomic mass. In the Modern...
What were the limitations of Döbereiner’s classification?
Limitations of Döbereiner’s classification: They do not work at elements which have very low or high mass. All elements could not fit into Dobereiner's traids. As the methods of calculating the...
Arrange the following elements in the increasing order of their metallic character: Mg, Ca, K, Ga
Metallic character increases according to this order Ga< Mg <Ca< K.
Arrange the following elements in increasing order of their atomic radii : Li, Be, F, N
Atomic radii increases according to the order: F < N < Be < Li. This is because down the group, the atomic size increases and across a period it decreases.
How do electronic configurations of elements change in second period of periodic table with increase in atomic numbers?
The change in electronic configuration is depicted as follows:
Name the element which is in: (a) First group and third period. (b) Seventeenth group and second period.
(a) Sodium is the element in the first group and third period. (b) Fluorine is the element in the second period and seventeenth group.
How does the valency of elements vary in going down a group of the periodic table?
All the elements in a group have the same valency while going down the group as they all have the same number of electrons in their outermost shell.
How does the valency of elements change on moving from left to right in the third period of the periodic table?
The valency of elements changes from left to right as at first there is an increase in valency from 1 to 4 and then it decreases to zero from group 15 in the 3rd period.
How does the number of valence electrons vary on moving from left to right: (i) In the first period of the periodic table? (ii) In the second period of the periodic table?
(i) The number of valence electrons increases by 1 (from 1 to 2) in the 1st period of the periodic table. (ii) The valence electrons increase by 7 (from 1 to 8) in the 2nd period of the periodic...
What happens to the metallic character of the elements as we go down in a group of the periodic table?
Down a group in the periodic table, the metallic character of elements increases as the tendency of an element to lose an electron increases down a group.
How do the atomic radii of elements change as we go from left to right in a period of the periodic table?
On moving from left to right across a period, the atomic size decreases due to an increase in the number of protons in the nucleus and the shell being the same.
What is the major characteristic of the first elements in the periods of the periodic table? What is the general name of such elements?
The major characteristic of the first elements in the periods of the periodic table is that they all have 1 valence electron. Such elements are known as alkali metals.
State whether the following statement is true or false: On-going down in a group of the periodic table, the number of valence electrons increases.
False. Down a group in the periodic table, the number of valence electrons remain the same. For example, from lithium to francium, all the alkali metals have 1 valence electron.
(a) What is the number of valence electrons in the atoms of first element in a period? (b) What is the usual number of valence electrons in the atoms of the last element in a period?
(a) There will be 1 valence electron in the atom of first element in a period. (b) There will be 8 valence electrons in the atom of last element in the period.
What property do all the elements in the same group of the periodic table as fluorine have in common?
The element fluorine is in group 17 of the periodic table, which is also known as the halogen group, and has a valency of 1. So, all the elements in the halogen group will have a valency equal to 1.
What property do all elements in the same column of the periodic table as boron have in common?
All elements in the same column of the periodic table as boron have 3 valence electrons in their ultimate shell.
(a) How does the chemical reactivity of alkali metals vary on going down in group 1 of the periodic table? (b) How does the chemical reactivity of the halogens vary on going down in group 17 of the periodic table?
(a) In group 1 of alkali metals, the chemical reactivity increases down the group from lithium to francium. (b) In group 17 of halogen elements, the chemical reactivity decreases down the group from...
How would the tendency to lose electrons change as we go from left to right across a period of the periodic table?
As we move from left to right in a period, the tendency of atoms to lose electrons decreases as the force of attraction between the nucleus and electrons increases. This is because the number of...
How would the tendency to gain electrons change on moving from left to right in a period of the periodic table?
As we move from left to right in a period, the tendency of atoms to gain electrons increases as more and more electrons get accommodated in the same shell.
Given alongside is a part of the periodic table: As we move horizontally from left to right: (i) What happens to the metallic character of the elements? (ii) What happens to the atomic size?
As we move horizontally from left to right, the following things happen: (i) Metallic character decreases. (ii) Atomic size decreases.
The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of element is: (a) Electron (b) Proton (c) Neutron (d) Meson
Option (b) is the answer.
The modern periodic table was prepared by: (a) Dobereiner (b) Newland (c) Bohr (d) Mendeleev
Option (c) is the answer.
An element X forms an oxide X2O3. In which group of Mendeleev’s periodic table is this element placed? (a) Group II (b) Group III (c) Group V (d) Group VIII
Option (b) is the answer.
Which of the following statement about modern periodic table is correct? (a) It has 18 horizontal rows known as periods (b) It has 7 vertical columns known as periods (c) It has 18 vertical columns known as groups (d) It has 7 horizontal rows known as groups
Option (c) is the answer.
Which of the following statement is correct in regard to the classification of elements ? (a) Elements in the periodic table are arranged on the basis of increasing atomic masses (b) Elements in Mendeleev’s periodic table are arranged on the basis of increasing atomic numbers (c) In modern periodic table, the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass (d) In modern periodic table, the isotopes of chlorine having different atomic masses are kept in the same group.
Option (d) is the answer.
The atomic numbers of four elements P, Q, R and S are 6, 18, 14 and 16 respectively. Out of these, the element known as metalloid is: (a) P (b) Q (c) R (d) S
Option (c) is the answer.
The three imaginary elements X,Y and Z represent a Doberieners triad. If the atomic mass of element X is 14 and that of element Y is 46,then the atomic mass of Element Z will be: (a) 28 (b) 60 (c) 78 (d) 72
Option (c) is the answer.
In Mendeleev’s periodic table, gaps were left for the elements to be discovered later on. An element which found a vacant place in the periodic table later on is: (a) Be (b) Si (c) Ge (d) Se
Option (c) is the answer.
The three elements having chemical symbols of Si, B and Ge are: (a) All metals (b) All non-metals (c) All metalloids (d) Si is metalloid and Ge is non-metal
Option is (c) is the answer.
According to Mendeleev’s periodic law, the elements were arranged in the periodic table in the order of: (a) Decreasing atomic numbers (b) Increasing atomic numbers (c) Decreasing atomic masses (d) Increasing atomic masses
Option (d) is the answer.
The Newland’s law of octaves for the classification of elements was found to be applicable only up to the element: (a) Potassium (b) Calcium (c) Cobalt (d) Phosphorus
Option (b) is the answer.
In Mendeleev’s periodic table, gap was not left for one of the element. This element is: (a) Gallium (b) Beryllium (c) Germanium (d) Scandium
Option (b) is the answer.
Name the scientist who prepared modern periodic table.
The modern periodic table was prepared by Henry Moseley.
(a) How could the modern periodic law remove various anomalies of Mendeleev’s periodic table? Explain with examples. (b) Is it possible to have an element having atomic number 1.5 placed between hydrogen and helium?
(a) Anomalies of Mendeleev’s periodic table: 1. Elements are arranged in increasing order of atomic number in modern periodic table, thus there was no need for keeping more than one element in one...
(a) State modern periodic law. (b) How does the electronic configuration of the atom of an element relate to its position in the modern periodic table?
(a) The modern periodic law states that the physical and chemical properties of an element is a periodic function of its atomic number. (b) The elements are arranged in the increasing order of...
(a) State any three limitations of Mendeleev’s classification of elements. (b) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his periodic table ? (c) Which group of elements was missing from Mendeleev’s original periodic table?
(a) Limitations of Mendeleev’s classification of elements: (i) It failed to explain the position of isotopes. (ii) The wrong order of atomic masses of some elements could not be explained. (iii) The...
(a) State Mendeleev’s periodic law. (b) What chemical properties of elements were used by Mendeleev in creating his periodic table?
(a) The physical and chemical properties of the elements are a periodic function of their atomic masses. It was the discovery of atomic number which led to a change in Mendeleev’s periodic law which...
Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Because of a similarity in their chemical properties, the two isotopes of chlorine have the same atomic number and chemical properties. The arrangement of elements is on the basis of increasing...
(a) Why did Mendeleev leave some gaps in his periodic table? (b) In Mendeleev’s periodic table, why was there no mention of noble gases like helium, neon and argon?
(a) In order to make sure that the elements having similar properties lie in the same vertical column (group), Mendeleev left some gaps in his periodic table. (b) The noble gases were not discovered...
(a) Why do we classify elements? (b) What were the two criteria used by Mendeleev to classify the elements in his periodic table?
(a) The elements are classified according to the properties possessed by the elements. Elements with similar properties fall in the same group and thus large number of elements got restricted to a...
(a) How do the properties of eka – aluminium element predicted by Mendeleev compare with the actual properties of gallium element? Explain your answer. (b) What names were given by Mendeleev to the then undiscovered elements (i) scandium (ii) gallium, and (iii) germanium?
(a) Eka-aluminium and gallium are the two different names for a single element. Eka-aluminium has same property like density, melting point etc as gallium element and it was proposed before the...
(a) State the merits of Mendeleev’s classification of elements. (b) Describe two anomalies of Mendeleev’s periodic classification of elements.
(a) Merits: 1. Predicted the existence of certain elements such as gallium, scandium and germanium. 2. Predicted the properties of various elements based on their positions in the periodic table. 3....
(a) State the periodic law on which Mendeleev’s periodic table was based. Why and how was this periodic law changed? (b) Explain why, the noble gases are placed in a separate group.
(a) According to Mendeleev’s periodic law, the physical and chemical properties of elements are a periodic function of their atomic masses. It was the discovery of atomic number which led to a...
What were the limitations of Newlands’ law of octaves?
(i) It was not applicable throughout the arrangements of elements in the periodic table. (ii) Those elements discovered after Newland’s octaves did not follow the law of octaves. (iii) The position...
(a) Did Dobereiner’s triads also exist in the columns of Newlands’ law of octaves? Explain your answer. (b) What were the limitations of Dobereiner’s classification of elements?
(a) Yes, Dobereiner's triads also exist in the columns of Newlands’ Octaves. This can be explained by taking the second column of the Newland’s classification of elements which has the elements...
What is Newlands’ law of octaves? Explain with an example.
According to the Newlands’ law of octaves, when elements are arranged in the order of their increasing atomic masses, the properties of the eighth element (starting from a given element) occur in a...
What is Dobereiner’s law of triads? Explain with the help of one example of a Dobereiner’s triad.
According to Dobereiner’s law of triads, when elements in the periodic table are arranged in an increasing order of their atomic masses, a group of elements share similar chemical properties. This...
Name three elements with completely filled outermost shells.
Helium, Neon, Argon are completely filled and appear under the category of noble gases.
(a) Name three elements that have a single electron in their outermost shells. (b) Name two elements that have two electrons in their outermost shells.
(a) Lithium, Sodium, Potassium are the elements having single electron in their outermost electron. They come under the category of alkali metals. (b) Magnesium and calcium have two electrons in...
What is the name of those elements which divide metals and non-metals in the periodic table?
Metalloid is the name of the group of elements which divide metals and non-metals in periodic table. They are the elements which share the properties of both metals and non-metals.
(a) On which side of the periodic table will you find metals? (b) On which side of the periodic table will you find non-metals?
(a) Metals are placed in left side of the periodic table. (b) Non-metals are placed in right side of the periodic table.
Where should hydrogen be placed in the modern periodic table? Give reason for your answer.
Hydrogen is placed at the topmost position of the periodic table because it resembles the properties of both alkali metals and halogens each. But it is placed in first group above the alkali metals...
(a) How were the positions of isotopes of an element decided in the modern periodic table? (b) How were the positions of cobalt and nickel resolved in the modern periodic table?
(a) Isotopes of an element are species that have the same atomic number but different atomic mass. So they are not given separate place in periodic table and are based on the atomic number of that...
(a) In the modem periodic table, which are the metals among the first ten elements? (b) What is the significance of atomic number in the modern classification of elements? Explain with the help of an example.
(a) In the modern periodic table, only lithium and beryllium are the metals among the first ten elements and the rest are non-metals. (b) The significance of atomic numbers in the periodic table is...
Give two examples each of (i) group 1 elements (ii) group 17 elements (iii) group 18 elements.
Two examples of each category are as follows: (i) Group 1: Lithium and Sodium. (ii) Group 17: Fluorine and Chlorine. (iii) Group 18: Neon and Argon.
(a) What is meant by (i) a group, and (it) a period, in a periodic table? (b) How many periods and groups are there in the long form of periodic table?
(a) (i) The vertical column of the periodic table is known as a group. (ii) The horizontal row of elements in a periodic table is known as a period. (b) In total, there are seven periods and...
Fill in the following blanks with suitable words: (a) Group 18 elements are called ______. (b) According to Newlands’ classification of elements, the properties of sulphur are similar to those of oxygen because sulphur is the ______ element starting from oxygen.
(a) Noble Gases. (b) Eighth.
Fill in the following blanks with suitable words: (a) The basis for modern periodic table is ______. (b) The horizontal rows in a periodic table are called ______.
(a) Atomic number. (b) Periods.
Fill in the following blanks with suitable words: (a) Group 1 elements are called ______. (b) Group 17 elements are known as ______.
(a) Alkali metals. (b) Halogens.
Which group of elements could be placed in Mendeleev’s periodic table later on, without disturbing the original order? Give reason.
The noble gases could be placed in Mendeleev’s periodic table later on, without disturbing the original order. Noble gases which are chemically least reactive and more stable could be placed in the...
State one example of a Dobereiner’s triad, showing in it that the atomic mass of middle element is half-way between those of the other two.
Lithium, sodium and potassium are said to be one of the triads in the Mendeleev’s periodic table. Lithium (atomic mass 7) is the first element in the triad and sodium being in the middle has atomic...
Name two elements whose properties were predicted on the basis of their positions in Mendeleev’s periodic table.
Eka- Aluminium (gallium) and Eka-Silicon (germanium) are the two elements whose properties were predicted on the basis of their positions in the periodic table without getting into details of the...
The three elements predicted by Mendeleev from the gaps in his periodic table were known as eka-boron, eka – aluminium and eka-silicon. What names were given to these elements when they were discovered later on?
Scandium, Gallium, Germanium are the three elements predicted by Mendeleev from the gaps in his periodic table and were known as eka-boron, eka – aluminium and eka-silicon.
Name two elements whose properties were predicted on the basis of their positions in Mendeleev’s periodic table.
Gallium and Scandium are the two elements whose properties are predicted on the basis of their positions in Mendeleev’s periodic table without going into further details.
In the classification of the then known elements, Mendeleev was guided by two factors. What are those two factors?
The factors that guided Mendeleev to classify the elements were: 1. Increasing atomic masses. 2. Grouping together the elements having the same physical and chemical properties.
What was the Mendeleev’s basis for the classification of elements?
As per Mendeleev, the basis for the classification of elements was atomic mass.
X and Y are the two elements having similar properties which obey Newlands’ law of octaves. How many elements are there in-between X and Y?
There will be six elements in between X and Y since X and Y are the two elements having similar properties and obey Newlands law of octaves.
A, B and C are the elements of a Dobereiner’s triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?
As per Dobereiner’s triad, the atomic mass of the middle element is the average of the atomic mass of first and third element. Given, Mass of A = 7 Mass of C = 39 Mass of B = (7+39)/2 =...
Name the scientists who gave the following laws in the early classification of elements: (a) Law of octaves (b) Law of triads.
The scientists who gave the respective laws are: (a) Newlands gave the law of octaves. (b) Dobereiner gave the law of triads.
Rewrite the following statements after correction, if necessary: (a) Groups have elements with consecutive atomic numbers. (b) Periods are the horizontal rows of elements. (c) Isotopes are the elements of the same group.
(a) Periods have elements with consecutive atomic numbers. (b) The given statement is correct. (c) The given statement is correct.
Name the Russian chemist who said that the properties of elements are a periodic function of their atomic masses.
The scientist who said that the properties of elements are a periodic function of their atomic masses was Mendeleev.
State whether the following statement is true or false: The elements in a group have consecutive atomic numbers.
False. The elements in a period have consecutive atomic numbers and not in the group.
State whether the following statement are true or false: (a) Newlands divided the elements into horizontal rows of eight element each. (b) According to Mendeleev’s periodic law, the properties of elements are a periodic function of their atomic numbers.
(a) False. Newlands divided the elements into horizontal rows of seven element each and the first and last elements ended up on the same note. (b) False. According to Mendeleev’s periodic law, the...
(a) On what basis did Mendeleev arrange the element in his periodic table. (b) On what basis are they arranged now?
(a) Mendeleev arranged the elements in his periodic table on the basis of atomic masses. (b) Now, the elements are arranged on the basis of atomic numbers.
Which of the following statements about the Modern Periodic Table is correct:
(a) It has 18 horizontal rows known as Periods
(b) It has 7 vertical columns known as Periods
(c) It has 18 vertical columns known as Groups
(d) It has 7 horizontal rows known as Groups
Solution: The answer is (c) It has 18 vertical columns known as Groups Explanation: The modern periodic table is divided into 18 groups and seven periods. Columns are referred to as groups, while...
Up to which element, the Law of Octaves was found to be applicable
(a) Oxygen
(b) Calcium
(c) Cobalt
(d) Potassium
Solution: Answer: Option (b) Calcium Explanation: Newland's law of octaves is applicable to elements with atomic masses up to 40 da, which corresponds to the elements up to and including Calcium....