Question

Assertion : Hydrides of group-16 elements show volatility in the order : 

H₂O > H₂S > H₂Se > H₂Te

Reason : Electronegativity of group-16 elements increases down the group from oxygen to tellurium.

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

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

The correct option is (d) A and R are false.

Explanation:

Hydrides of group-16 elements show volatility in the order : 

H₂S > H₂Se > H₂Te > H₂O 

Oxygen is most electronegative than other elements of group-16, it undergoes hydrogen bonding. Due to strong intermolecular hydrogen bonding in H₂O, it shows lowest volatility. 

As the size of the atom increases regularly from sulphur to tellurium, van der Waals' forces of attraction increase and hence volatility decreases from H₂S to H₂Te.