Question

H₂E (E = 0, S, Se, Te तथा Po) के लिए तापीय स्थायित्व का सही क्रम है :
(1) H₂S < H₂O < H₂Se < H₂Te < H₂Po
(2) H₂O < H₂S < H₂Se < H₂Te < H₂Po
(3) H₂Po < H₂Te < H₂Se < H₂S < H₂O
(4) H₂Se < H₂Te < H₂Po < H₂O < H₂S

Answer 1

(3) is the correct answer

Explanation:

O,S,Se,Te and Po are the elements of oxygen family.

On going up to down in a group of periodic table the size of elements decreases which will effect the bond strength of compound. Due to their bonding ability with another atom also decreases on going up to down hence they will require low temperature to break down bonds as compare the hydrides of above elements.

so order will $H_{2}Po< H_{2}Te< H_{2}Se< H_{2}S< H_{2}O$