The first law of thermodynamics for an isothermal process is:

Two vessels $A$ and $B$ are connected via a stopcock. Vessel $A$ is filled with a gas at a certain pressure. The entire assembly is immersed in water and allowed to reach thermal equilibrium. After opening the stopcock,the gas from vessel $A$ expands into vessel $B$,and no change in temperature is observed. Which of the following statements is true?

What is the change in internal energy when a system releases $8 \ kJ$ of heat and performs $660 \ J$ of work on the surroundings (in $J$)?

For the gaseous reaction involving the complete combustion of isobutane,which of the following relations holds true?

Which one of the following equations does not correctly represent the first law of thermodynamics for the given processes involving an ideal gas? (Assume non-expansion work is zero)

What is the internal energy change when $62 \ J$ of work is done on the system and $128 \ J$ of heat is transferred to the surrounding (in $J$)?