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.
Answer & explanation
Correct answer: option 2
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