Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: In the light of the above statements, choose the correct answer from the options given below:
- A is true but R is false.
- Both A and R are true but R is NOT the correct explanation of A.
- A is false but R is true.
- Both A and R are true and R is the correct explanation of A.
Answer
(4) Both A and R are true and R is the correct explanation of A.
Solution
Group 13 (ns2np1): down the group the ns2 pair becomes reluctant to take part in bonding (inert pair effect).
Hence the +1 state becomes more stable down the group, Ga+ < In+ < Tl+ (Tl+ is more stable than Tl3+), so A is true.
R is true and is exactly the reason for this order, so R correctly explains A.
Answer: (4)