Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is false but Statement II is true
- Statement I is true but Statement II is false
Answer
(4) Statement I is true but Statement II is false
Solution
Statement I: the bond dissociation enthalpies ( kJ mol-1) are Cl2 242.6, Br2 192.8, F2 158.8 and I2 151.1.
F2 is unusually low because the lone pairs on the two small F atoms repel strongly, so the order is Cl2 > Br2 > F2 > I2 and Statement I is true.
Statement II: a metal ion in a higher oxidation state polarises the anion more, so its halide is more covalent. Thus SnCl4, PbCl4 and UF6 are more covalent than SnCl2, PbCl2 and UF4; the trend UF4 > UF6 is wrong, so Statement II is false.
Answer: (4)