Is the melting of ice an adiabatic or an isothermal process?

In an isothermal process,the volume of an ideal gas is halved. One can say that:

$Assertion :$ The isothermal curves intersect each other at a certain point.
$Reason :$ The isothermal change takes place slowly,so,the isothermal curves have very little slope.

$A$ sample of an ideal gas undergoes an isothermal expansion. If $dQ$,$dU$,and $dW$ represent the amount of heat supplied,the change in internal energy,and the work done respectively,then:

When heat is given to a gas in an isothermal process,then there will be

Obtain an expression for work done by an ideal gas in an isothermal expansion.