Question

The decreasing order of the boiling points of the following hydrides
(i) `NH_3` (ii) `PH_3`
(iii) `AsH_3` (iv) `SbH_3`
(v) `H_2O` is
A. `(v) gt (iv) gt (i) gt (iii) gt (ii)`
B. `(v) gt (i) gt (ii) gt (iii) gt (iv)`
C. `(ii) gt (iv) gt (iii) gt (i) gt (v)`
D. `(iv) gt (iii) gt (i) gt (ii) gt (v)`

Answer 1

Correct Answer - A
`H_2O` has the highest boiling point on account of hydrogen bonding while `PH_3` has the lowest boiling point on account of lowest molecular mass and absence of `H-` bonding. This confirms the answer. `SbH_3` has the 2nd highest boiling point on account of high molecular mass. `NH_3` has higher boiling point than `AsH_3` on account of hydrogen bonding.