Question

The properties of hydrides of oxygen family members that decrease down the group are :

• A. bond angle
• B. covalent nature
• C. thermal stability
• D. dissociation constant

Answer 1

Answer: (A), (C)

The correct options are
A bond angle
C thermal stability

(A) Hydrides : $H_{2}O{H}_{2}S{H}_{2}Se{H}_{2}Te$
Bond angle : ${104}^0{92}^0{91}^0{90}^0$
(B) Covalent nature : As the size of the anion increases, covalent character increases down the group.
(C) Thermal stability: With increase in temperature M - H bond becomes weaker and thus the thermal stability decreases from top to bottom.
(D) Dissociation constant increases from top to bottom. Thus it is $1\ast {10}^{-14};1\ast {10}^{-7};1\ast {10}^{-4}and2\ast {10}^{-1}$ for $H_{2}O,H_{2}S,H_{2}Seand{H}_{2}Te$ respectively.