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

If the initial internal energy of a system is $U_1$,and it absorbs $450 \ J$ of heat from the surroundings and performs $600 \ J$ of work,what will be the final internal energy of the system?

For the reaction $FeCO_{3(s)} \to FeO_{(s)} + CO_{2(g)}$,$\Delta H = 82.8 \ kJ$ at $25 \ ^oC$. What is $\Delta U$ at $25 \ ^oC$ in $kJ$?

$A$ certain mass of an ideal gas absorbs $80 \ kJ$ heat and the gas is expanded from $2 \ L$ to $10 \ L$ at a constant pressure of $25 \ bar$. What is $\Delta U$ for the gas in the process in $kJ$? $(1 \ bar-L = 100 \ J)$

Calculate the change in internal energy of the system if $20 \ kJ$ of work is done on the system and it releases $10 \ kJ$ of heat in a particular reaction. (in $kJ$)

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 $kJ$)?