Question

Arrange the following in the increasing order of melting points
(a)`NH_3`, (b)`CH_3NH_2` , (c )`(CH_3)_2NH` , (d)`(CH_3)_3N`
A. a lt bltc lt d
B. dlt cltb lt a
C. a lt dltc lt b
D. None of these.

Answer 1

Correct Answer - B
M.pt. of `NH_3CH_3NH_2, (CH_3)_2NH, (CH_3)N` are `-77.7^@ C , -92^@ C, -96^@ C and -117^@ C`.The reason is H-bonding which is maximum in `NH_3` and there is no H-bonding in trimethylamine