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 staiblity of salts with common anion depends on polarising power of cation. Greater the polarising power, lower be their thermal stability. Hence,
$BeC{O}_3\left(IV\right)<MgC{O}_3\left(II\right)<CaC{O}_3\left(III\right)<K_{2}C{O}_3\left(I\right)$