I NEED HELP QUICK In one cycle of any heat engine

A. the net work done is larger than the heat exhausted.
B. more heat flows from the engine than enters the engine.
C. The internal energy of the engine does not change.
D. the net heat flow is zero.​​

"why is graphite used instead of gold or copper wires to conduct electricity in very hot situations such as an industrial kiln? " that's the question, but the thing is, i don't even understand what an "industrial kiln" xd assistance would be < 3

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Starting with only the balmer series light (visible light), how could we ensure that the solar panels generate a current that mark can use for his power station? a)by gradually increasing the brightness (amount) of light that we shine on it. b)by gradually increasing the frequency of the light we shine on it. c)by gradually increasing the wavelength of the light that we shine on it.