How many of the following nitrates of metal ‘M’ decompose on heating similar to as given below in the scheme? (where;M=Li,Be,Mg,K,Ca,Sr,Na,Rb,Ba) 

Metal nitrate $\stackrel{\mathrm{Heat}}{\to }$metal oxide+ nitrogen dioxide+oxygen gas.

Alkaline earth metal nitrates decompose in the following manner:

 Metal nitrate $\stackrel{\mathrm{Heat}}{\to }$metal oxide + nitrogen dioxide + oxygen gas.

Thus, out of the given elements Be, Mg, Ca, Sr and Ba will show this behavior. But, Li due to it’s diagonal relationship with Mg, also shows similar kind of reaction.