Match the correct ionization enthalpies and electron gain enthalpies of the following elements.

Elements


\(\Delta H_1\) 


\(\Delta H_2\)


\(\Delta_{eg}H\)

(i)

Most reactive non-metal

A.

419

3051

-48

(ii)

Most reactive metal

B.

1681

3374

-328

(iii)

Least reactive element

C.

738

1451

-40

(iv)

Metal forming binary halide

D.

2372

5251

+48

Codes

A B C D
1. ii i iv iii
2. i ii iii iv
3. i iv iii ii
4. iv i iii ii
 
Hint: Most electronegative element has most negative electron gain enthalpy

(i) Most reactive non-metal has high H1 and H2 and most negative egH. Therefore, the element is B.

(ii) Most reactive metal has low H1 and high H2 (because the second electron has to be lost from noble gas configuration) and has small negative egH. Therefore, the element is A.

(iii) Noble gases are the least reactive elements. They have very high H1 and H2 and have positive egH values. Thus, the element is D.

(iv) Metal forming binary halides are alkaline earth metals. They have H1 and H2 values little higher than those of most reactive metals (such as A) and have comparatively slightly less negatice egH values. Thus, the element is C.