Question

In which of the following pairs the radii of second species is greater than that of first?
A K, Ca
B H, He
C Mg+, Mg2+
D O2–, O–

Answer 1

Explanation:

Consider the radius of the given species:-

A) Na is larger than Mg as size decreases as we move across a period from left to right.

B) O

2−

<N

3−

; Greater the electrons, more the repulsion and hence larger size.

C) Li

+

>Be

2+

; Greater effective nuclear charge.

D) Ba

2+

>Sr

2+

; Size increases as we move down a period.

Hence, option B is the right answer.

Answered by Manjiri