In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question. Assertion (A): The carbonate of lithium decomposes easily on heating to form lithium oxide and CO 2 . Reason (R) : Lithium being very small in size polarises large carbonate ion leading to the formation of more stable Li 2 O and CO 2 . (i) Both A and R are correct and R is the correct explanation of A. (ii) Both A and R are correct but R is not the correct explanation of A. (iii) Both A and R are not correct (iv) A is not correct but R is correct.

Question

Philoid · Accepted Answer

(i) Both A and R are correct and R is the correct explanation of A.

Explanation: Unlike other alkali metal carbonates which are stable in heat Lithium being very small in size polarises a large CO₃^2– ion leading to the formation of more stable Li₂O and CO₂.

Li₂CO₃→ Li₂O + CO₂

Polarisation is the distortion of electron cloud of the anion CO₃^2- by the cation Li²⁺.