Examine the following statements:
(i) Work is high grade energy
(ii) It is possible for a heat engine to produce work in a cycle by exchanging heat with bodies at same temperature
(iii) It is impossible to construct a device which operating in a cycle will produce no other effect other than transfer of heat from a cooler to a hotter body

Correct option is C

1. High grade energy refers to energy that can be fully converted into work.
Work is organized energy, and can be 100% converted into heat or other energy forms.
Hence, it is considered high-grade compared to heat, which is low-grade energy because it cannot be fully converted to work (due to the Second Law of Thermodynamics).

2. This violates the Kelvin-Planck statement of the Second Law of Thermodynamics, which states:

"It is impossible to construct a device operating in a cycle that converts all the heat into work with no other effect."
A heat engine must exchange heat with at least two reservoirs at different temperatures (source and sink) to produce work.
So, heat exchange at same temperature alone cannot produce work.

3. "It is impossible to construct a cyclic device whose sole effect is to transfer heat from a cooler body to a hotter body without any work input."
So, heat cannot flow spontaneously from cold to hot without external work.