(b) Select the correct answer:

(i) Across a period, the ionisation potential ………… [increases, decreases, remains the same]

(ii) Down the group, electron affinity ………… [increases, decreases, remains the same] 

(c) Choose the correct answer from the choice given:

(i) In the periodic table, alkali metals are placed in group A : 1, B : 11, C : 17, D : 18.

(ii) Which of the following properties do not match with elements of the halogen family?

A. They have seven electrons in their valence shell.

B. They are highly reactive chemically.

C. They are metallic in nature.

D. They are diatomic in their molecular form. 

(d) State the group and period of the element having three shells with three electrons in the valence shell.

Answers:

(a) Because of the increase in the nuclear pull, the oxidising power of the elements increases from left to right along a period.

(b)

(i) Across a period, the ionisation increases.

(ii) Down the group, electron affinity decreases.

(c)

(i) Correct Answer is option A; Explanation: In the periodic table, alkali metals are placed in group 1.

(ii) Correct Answer is option C; Explanation: The elements in the halogen series are non-metals.

(d) The element having three shells with three electrons in the valence shell is from 3^rd group and 3^rd period.