Onsider the following cyclic process carried out in two steps on a gas: step 1: 42 j of heat is added to the gas, and 14 j of expansion work is performed. step 2: 53 j of heat is removed from the gas as the gas is compressed back to the initial state. calculate the work for the gas compression in step 2.

W = -25 J

Explanation:

For a cyclic process, the variation of internal energy (ΔU) must be 0. It means that ΔU from step 1 must be equal to ΔU from step 2. For the first law of the thermodynamics, the energy must be conserved, so:

ΔU = Q - W, from each step. Q is the heat and W the work

When the heat is gained by the system, the process is endothermic, so Q >0, when the system loses heat, the process is exothermic, and Q<0. When the system is expanding W>0, and when it is compressing, W<0.

From step 1:

ΔU = 42 - 14

ΔU = 28 J

From step 2:

28 = -53 - W

W = -53 + 28

W = -25 J

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.