Question

Which of the following compound decomposes at the highest temperature?

• A. $SrC{O}_3$
• B. $BaC{O}_3$
• C. $CaC{O}_3$
• D. $MgC{O}_3$

Answer 1

Answer: (B)

$BaC{O}_3$

$BaC{O}_3$ decomposes at highest temp. All the carbonates decompose on heating to give $C{O}_2$ and metal oxide.$MC{O}_3\stackrel{\Delta }{\to }MO+C{O}_2$ The stability of carbonate towards heat depends upon the stability of the resulting metal oxide. More is the stability of the resulting metal oxide lesser is the stability of the carbonate towards heat and vice- versa.
So as we down the group stability of oxides of alkaline earth metal increases, so compound decomposes at the highest temperature will be $BaC{O}_3$.
Hence option B is correct.