Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Statement I is true but Statement II is false
- Both Statement I and Statement II are false
- Statement I is false but Statement II is true
- Both Statement I and Statement II are true
Answer
(4) Both Statement I and Statement II are true
Solution
Statement I: iH1 (kJ mol-1): Na 496 < Li 520 < Cl 1256 < F 1681
∵ IE decreases down a group and is much higher for halogens ⇒ Statement I is true
Statement II: egH (kJ mol-1): Na −53, Li −60, F −328, Cl −349
∵ small 2p subshell of F has strong e⁻–e⁻ repulsion ⇒ Cl more negative than F ⇒ Na < Li < F < Cl ⇒ Statement II is true
Answer: (4)