Question

In terms of thermal stability of the alkali metal hydrides, which one is the most stable?

• A. NaH
• B. RbH
• C. LiH
• D. KH

Answer 1

Answer: (C)

Metallic hydrides are hydrogen compounds forming bonds with other metal elements. So, Li is the most stable element as it is the least reactive element. Also as we go down the group, the size of the metal increases and the X - H bond becomes weaker.
Hence, LiH is the correct answer.