The change in internal energy of a system depends upon

Which of the following reactions shows work of compression?

Calculate change in enthalpy when 39 g acetylene is completely burnt with oxygen and enthalpy of combustion of acetylene is $$-$$1300 kJ/mol.

(At. mass C = 12, H = 1)

An ideal gas on isothermal reversible compression from 10L to 5L performs 1730J of work at 300 K. Calculate number of moles of gas involved in compression? (R = 8.314 J K$$^{-1}$$ mol$$^{-1}$$)