A reversible heat engine $$(E)$$ operating in a cycle interacts with three reservoirs $$1,$$ $$2$$ and $$3$$ maintained at temperature $${T_1} = 500K,$$ $${T_2} = 400K,$$ and $${T_3} = 300K,$$ respectively. The engine receives $$10$$ $$kJ$$ of heat from reservoir $$1$$ and rejects $$3$$ $$kJ$$ to reservoir $$3.$$ The net work output, $${W_{net}}$$ (in $$kJ$$) from the engine is

An ideal gas of mass $$m$$ is contained in a rigid tank of volume $$V$$ at a pressure $$P.$$ During a reversible process its pressure reduces to $${P_1}.$$ Following statements are made regarding the process.
$$(P)$$ Heat is transferred from the gas.
$$(Q)$$ Work done by the gas is zero.
$$(R)$$ Entropy of the gas remains constant.
$$(S)$$ Entropy of the gas decreases.

Among the above statements, the correct ones are