Question

The following compounds have been arranged in order of their increasing thermal stabilities. Identify the correct order :
$K_{2}C{O}_3\left(I\right),MgC{O}_3\left(II\right),CaC{O}_3\left(III\right),BeC{O}_3\left(IV\right)$

• A. $I<II<III<IV$
• B. $IV<II<III<I$
• C. $IV<II<I<III$
• D. $II<IV<III<I$

Answer 1

The correct option is B $IV<II<III<I$

Thermal stability is the stability of a molecule at high temperatures; i.e. a molecule with more stability has more resistance to decomposition at high temperatures. Thermal stability also describes, as defined by Schmidt (1928), the stability of a water body and its resistance to mixing.
As the size of the ion of the carbonate increses thermal stability also increases.
So Be,Mg,Ca belongs to IIA group so Be is having least size Ca is having large size so $CaC{O}_3$ thermally stable than $MgC{O}_3$ than $BeC{O}_{3}2$.and pottasium is having more size than (IA group element) IIA group element.so $K_{2}C{O}_3$ is more stable than all the other carbonates.
So the correct order of thermal stability is $IV<II<III<I$.
Hence option B is the correct.
Hence correct option is 1.