Question

Among $CaH_{2}, \, NH_{3}, \, NaH \,$ and $\, B_{2}H_{6},$ which are covalent hydride?

• A. $NH_{3} \,$ and $\, B_{2}H_{6}$
• B. $NaH \,$ and $\, CaH_{2}$
• C. $NaH \,$ and $\, NH_{3}$
• D. $CaH_{2} \, $ and $\, \, B_{2}H_{6}$

Answer 1

Answer: (A)

Hydrides are binary compounds of hydrogen. These can be classified in four groups viz :
(i) Ionic hydrides e.g., $NaH, \, CaH_{2}, \, LiH \, etc.$
(ii) Covalent hydrides e.g., $B_{2}H_{6}, \, NH_{3}, \, SbH_{3} \, etc.$
(iii) Polynuclear hydrides e.g., $LiAlH_{4}, \, NaBH_{4} \, etc.$
(iv) Interstitial hydrides, in which hydrogen is trapped in the interstial spaces of transition metals.