Assertion: With rise in temperature, there is a chance of distortion in solids.

Reason: An ideal crystal contains the same lattice points throughout the whole crystal.

Assertion and Reason both are correct statements and reason is not the correct explanation for assertion.

An ideal crystal is the one which has the same unit cell (containing the same lattice points) throughout the whole of the crystal.

At absolute zero, most of the ionic crystals are ideal. But with the rise in temperature, there is a chance of distortion. The defect may appear

(i) At a point

(ii) Along a line or

(iii) over a surface