Statement (I) : BP of H₂S < H₂Se < H₂Te

Statement (II) : Down the group vanderwaal's forces become strong

Down the group in the hydrides of 15^th , 16^th , 17^th groups

A) Affinity towards Hydrogen decreases

B) X-H bond enthalpy decreases

C) X-H bond length increases

D) Thermal stability decreases

E) Acidic strength (K_a) increases

F) Reducing power increases

Thus 'K_a' of H₂O< H₂S < H₂Se < H₂Te

bond dissociation enthalpy  of  H₂O> H₂S > H₂Se > H₂Te

X-H bond length O-H < S-H < Se-H < Te-H

from H₂O to H₂Te molecular weight and molecular size increases , vanderwaals forces become stronger

 Except MP & Bp - H₂O< H₂S < H₂Se < H₂Te

But H₂O molecules are associated through intermolecular H- bonding.

It has abnormally high MP & BP

MP & BP order will be  H₂S< H₂Se < H₂Te< H₂O  (or) H₂O > H₂Te> H₂Se > H₂S