Alkali and alkali earth metal carbonates and bicarbonates decomposition Which of the following can not decompose on heating to give $\ce{CO_2}$?

$\ce{Li_2CO_3}$
$\ce{Na_2CO_3}$
$\ce{KHCO_3}$
$\ce{BaCO_3}$


What I have read till now: Lithium carbonate is not so stable to heat and bicarbonates of alkali metals decompose at approximately $\pu{300 ^\circ C}$. The stability of alkaline earth metals increases down the group and they decompose on red heating.
This only leaves us with one option as correct (2nd), but what is the reaction of decomposition of $\ce{Na_2CO_3}$?
From your question, the heating temperature is unclear. See these links for sodium and lithium carbonates, the hydrocarbonate or barium.

They are all also mentioned on Wikipedia. 

In other words, they all seem to decompose at some point, so what is meant by heating? 

The reaction for sodium carbonate decompositon at melting point should be: 

$$\ce{Na2CO3 -&gt; Na2O + CO2}$$