In the vander Waals' equation, the constant 'a' and 'b' with temperature shows which trend:
(a) both remains same
(b) 'a' remains same, 'b' varies
(c) 'a' varies, 'b' remains same
(d) both varies
(d) This is one of the limitation of vander Waal's equation.
'a' is measure of force, which is sensitive for distance, with increase in temp, the distance between molecule increase,so magnitude of force decrease. 'b' is measure of size, which is not so sensitive as 'a' . but it also changes.