Classification of Elements and Periodicity in Properties

Given below are two statements: In the light of the above statements, choose the most appropriate from the options given below

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is false but Statement II is true
4. Statement I is true but Statement II is false

Answer

(3) Statement I is false but Statement II is true

Solution

egH (kJ mol-1):

Group 17: F -328, Cl -349, Br -325, I -295

Group 16: O -141, S -200, Se -195, Te -190, Po -174

∵ F and O are very small ⇒ strong electron–electron repulsion in the compact 2p subshell ⇒ less negative egH than the next member

Statement I: Cl (not F) is most negative ⇒ Statement I is false

Statement II: O is least negative in group 16 ⇒ Statement II is true

Answer: (3)