NEET Chemistry The s-Block Elements Questions Solved

NEET - 2008

The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrides decreases in which of the following orders?

(a) CsH>RbH>KH>NaH>LiH

(b) KH>NaH>LiH>CsH>RbH

(c) NaH>LiH>KH>RbH>CsH

(d) LiH>NaH>KH>RbH>CsH

(d) Key Idea: Small anion forms stable compounds with small cation.

The thermal stability of alkali metal hydrides decreases as:

    LiH>NaH>KH>RbH>CsH

because the size of cation increase as:

     Li+<Na+<K+<Rb+<Cs+

Difficulty Level:

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