Question

When we heat an object, it expands. Is work done by the object in this process? Is heat given to the object equal to the increase in its internal energy?

Answer 1

When we heat an object, it expands, i.e. its volume increases.
Work done by the system, $\Delta W=P\Delta V$

Using the first law of thermodynamics, we get
$∆$Q = $∆U+∆W$

Since the volume changes,$∆$W has some non-zero positive value. Thus, heat given to the object is not equal to the increase in the internal energy of the system.