The pair of species having identical shapes for molecules of both species is

Which one of the following compounds has the smallest bond angle in its molecule?

According to the kinetic theory of gases, in an ideal gas, between two successive collisions of a gas molecule travels

The internal energy change when a system goes from state A to B is 40 kJ/mole. If the system goes from A to B by a reversible path and returns to state A by an irreversible path what would be the net change in internal energy?