In This post you will get answer of Q.
During the melting of a slab of ice at $273 ,K$ at atmospheric pressure
When a slab of ice at $ 273,K $ melts, volume of water formed is less than the volume of ice melted ie, volume decreases. Therefore, work done by ice-water system is negative or in other words positive work is done by the atmosphere on the ice-water system. This increases the internal energy of ice-water system.