If $Q$ is the heat liberated from the system and $W$ is the work done on the system,then the first law of thermodynamics can be written as:

$\Delta U$ is equal to

$A$ gas is allowed to expand in an insulated container against a constant external pressure of $2.5 \ bar$ from $4.5 \ dm^3$ to $7 \times 10^{-3} \ m^3$. What is the change in internal energy of the gas (in $J$)?

$A$ gas in a frictionless piston cylinder at a constant pressure of $1 \ atm$ expands from a volume of $2 \ L$ to $6 \ L$. In doing so,it absorbs $800 \ J$ of heat from the surroundings. The change in internal energy of the process is ..... $J$.

The work done by the system is $8 \, J$. When $40 \, J$ of heat is supplied to the system,the change in internal energy of the system during the process is ...... $J$.

Which of the following statements is true regarding the universe according to the laws of thermodynamics?