Question

Select the correct order regarding the relative thermal stabilities of alkali metal halides.

• A. $CsCl>RbCl>KCl>NaCl>LiCl$
• B. $LiCl>NaCl>KCl>RbCl>CsCl$
• C. $CsCl>RbCl<KCl>NaCl<LiCl$
• D. $CsCl>RbCl>KCl<NaCl>LiCl$

Answer 1

The correct option is B $LiCl>NaCl>KCl>RbCl>CsCl$

As we go down the group, ionic radius increases and so, the bond length of metal halide also increases. Due to the longer bond length, stability of halides decreases. The correct order of thermal stability is as follows:

$LiCl>NaCl>KCl>RbCl>CsCl$