In which of the following processes, heat is neither absorbed nor released by a system?

Increase in tempertaure of a gas filled in a container would lead to :

The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is

A sample of 0.1 g of water at 100°C and normal pressure (1.013 × 10⁵ N m^–2) requires 54 cal of heat energy to convert to steam at 100°C. If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample, is