Answer:-683 cal
Explanation:
Given
Heat released by system Q=-255 cal
as heat released is taken as negative and vice-versa
Work done by system W=428 cal
From First law of thermodynamics
=change in internal Energy

Answer:
potential energy is a type of energy an object has because of it's position
What happens is the potential value of the conductor decreases due to the presence of second conductor
as the capacitance is given by C = q/v
the value of v deceases as v-v1
thus the new capacitance is = C' = q/v-v1 thus the lowering of v increases the capacitance