Question

First and second ionisation enthalpies (in kJ/mol) of few elements are given below.

Element	$IE_{1}$	$IE_{2}$
(i)	520	7300
(ii)	900	1760
(iii)	1680	3380
(iv)	2082	3963

Which of the above elements will form halides with formula $MX_{2}$?

• A. (i) and (ii)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (i) and (iv)

Answer 1

Answer: (C)

(ii) and (iii)

Answer 2

: (ii) is a reactive metal from second group, and (iii) is a reactive non – metal from 17^th group. For second group elements, the difference in successive IE is less. The compound formed will be $MX_{2}$.