Based on the first law of thermodynamics,which of the following is correct?

If $2 \ kJ$ of heat is released from the system and $6 \ kJ$ of work is done on the system,what is the internal energy change $(\Delta U)$ of the system?

In a process,the work done by the system is equal to the change in its internal energy. Then the process will be ...........

When $1 \ mol$ of ice melts at $0 \ ^oC$ and a constant pressure of $1 \ atm$,the system absorbs $1440 \ cal$ of heat. If the molar volumes of ice and water are $0.0196 \ L$ and $0.0180 \ L$ respectively,calculate the change in internal energy $(\Delta U)$ of the system in $cal$.

In a process,$701 \, J$ of heat is absorbed by a system and $394 \, J$ of work is done by the system. What is the change in internal energy for the process (in $, J$)?

At the $1$ bar pressure,the volume of a gas is $0.6 \ L$. If the gas receives $122 \ J$ of heat at $1$ bar pressure,the volume becomes $2 \ L$. Calculate the change in its internal energy. $(1 \ L \cdot bar = 101.32 \ J)$