Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Statement I is false but Statement II is true
- Both Statement I and Statement II are false
- Statement I is true but Statement II is false
- Both Statement I and Statement II are true
Answer
(4) Both Statement I and Statement II are true
Solution
Statement I: b.p. (K): HCl 189, HBr 206, HI 238, HF 293.
From HCl to HI the b.p. rises with size (stronger van der Waals forces), while HF has the highest b.p. due to strong H-bonding, so the order HCl < HBr < HI < HF is true.
Statement II: m.p. (K): HCl 159, HBr 186, HF 190, HI 222, so the order HCl < HBr < HF < HI is also true.
(As per NCERT, Table 7.8: the m.p. of HF lies between those of HBr and HI.)
Answer: (4)