A gas expands when 867 J of energy is added to it by heat. The expanding gas
does 623 J of work on its surroundings.
What is the overall change in the internal energy of the gas?

it is called kinetic energy

answer; equivalent to a one(1) horsepower motor;

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods

the answer to this is proletariats.

hope this : )