7. According to Kelvin-Planck's statement of second law of thermodynamics,
Options
A. it is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
B. it is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
C. it is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body
Correct Answer: pv = constant, if T is kept constant
10. According to Gay-Lussac law, the absolute pressure of a given mass of a perfect gas varies __________ as its absolute temperature, when the volume remains constant.