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 true but Statement II is false
- Statement I is false but Statement II is true
Answer
(2) Both Statement I and Statement II are false
Solution
Statement I: i H2 (kJ mol-1): B 2427, Al 1816, Ga 1979.
∵ The 10 poorly shielding 3d electrons in Ga raise its effective nuclear charge ⇒ Ga > Al.
⇒ Correct order B > Ga > Al ⇒ Statement I is false.
Statement II: i H1 (kJ mol-1): Si 786, Ge 761, Sn 708, Pb 715 ⇒ Sn < Pb < Ge < Si.
(Pb > Sn because of poor shielding by 4f and 5d electrons.) ⇒ Statement II is false.
Answer: (2)