Question

Assertion (A): The carbonate of lithium decomposes easily on heating to form lithium oxide and $C{O}_2$

Reason (R): Lithium being very small in size polarises large carbonate ions leading to the formation of more stable $L{i}_{2}OandC{O}_2$.

• A. A is not correct but R is correct.
  
  
• B. Both A and R are correct and R is the correct explanation of A.
  
  
• C. Both A and R are not correct.
  
  
• D. Both A and R are correct and R is not the correct explanation of A.
  
  

Answer 1

The correct option is B Both A and R are correct and R is the correct explanation of A.



Analysing the assertion

The thermal stability of carbonates increases down the group. So, we can say that carbonate of lithium decomposes easily on heating to form lithium oxide and $C{O}_2$ and assertion is correct.

Analysing the reason

$L{i}_{2}C{O}_3$ is the least stable. Due to the small size of $L{i}^{+}$, it has strong polarising power which distorts the electron cloud of $C{O}_2^{3-}$ ions.

Also, the higher lattice energy of $L{i}_{2}OthanL{i}_{2}C{O}_3$ also favours the decomposition of $L{i}_{2}C{O}_3$.

$L{i}_{2}C{O}_3\to L{i}_{2}O+C{O}_2$

So, the statement of reason is also correct and it is the correct explanation of assertion.

Correct answer is option (A).