p-Block Elements (Group 15–18)

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 most appropriate from the options given below:

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is NOT the correct explanation of A.
3. A is false but R is true.
4. A is true but R is false.

Answer

(1) Both A and R are true and R is the correct explanation of A.

Solution

Down group 16: size of E ↑ ⇒ H–E bond dissociation enthalpy ↓ (H2S 347, H2Se 276, H2Te 238 kJ mol-1) ⇒ R is true

∵ the weaker H–Te bond releases H+ more easily ⇒ acidity: H2O < H2S < H2Se < H2Te ⇒ A is true

⇒ R (lower bond enthalpy) is the reason for A

Answer: (1)