What variables are represented by the formula for the first law of thermodynamics? check all that apply. internal energy chemical energy electrical energy heat work?

I think internal energy and heat work are the variables that is represented by the formula for the first law of thermodynamics. According to the first law of thermodynamics the change in internal energy of a system is equal to the net heat transfer into the systems minus the net work done by the system. The equation is; ΔU = Q - W
where ΔU is the change in internal energy of the system, Q is the net heat transfer into the system while W is the work done on or by the system.

Answerstudying coal cumbustion as an energy source;

Answer is: hydrogen is being oxidized.chemical reaction: co₂ + h₂ → co + h₂o.oxidation half reaction: h₂ → 2h⁺ + 2e⁻.reduction half reaction: c⁺⁴ + 2e⁻ → c⁺².oxidation is increase of oxidation number, hydrogen change oxidation number from neutral charge (in molecule of hydrogen) to oxidation number +1 (in water).