What is the change in internal energy if a system does $140 \ kJ$ of work on the surroundings and $40 \ kJ$ of heat is added to the system (in $kJ$)?

Which of the following processes exhibits a decrease in the internal energy of a system?

$A$ gas expands isothermally against a constant external pressure of $1 \ bar$ from $10 \ dm^3$ to $20 \ dm^3$ by absorbing $800 \ J$ of heat from the surroundings. Calculate the value of $\Delta U$. (in $J$)

For the gas phase reaction $A_{2(g)} + B_{2(g)} \rightarrow 2AB_{(g)}$ taking place at constant pressure and temperature where all gases are behaving ideally,which of the following must be correct?

$A$ gas expands against a variable pressure given by $P = \frac{20}{V}$ ($P$ in $atm$ and $V$ in $L$). During expansion from volume of $1 \ L$ to $10 \ L$,the gas undergoes an increase in internal energy of $400 \ J$. How much heat is absorbed by gas during expansion (in $J$)? (Given: $1 \ L \cdot atm = 101.3 \ J$)

For the reaction $CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$ at constant temperature and pressure,which of the following statements is correct?