In how many ways can the internal energy of a system be changed?

The first law of thermodynamics is concerned with the conservation of

In a thermodynamic process,the pressure of a fixed mass of a gas is changed in such a manner that the gas releases $20 \ J$ of heat and $8 \ J$ of work is done on the gas. If the initial internal energy of the gas was $30 \ J$,the final internal energy will be ...... $J$.

$A$ thermodynamic system is changed from state $(P_1, V_1)$ to $(P_2, V_2)$ by two different processes. The quantity which will remain the same is

The latent heat of vaporisation of water is $2240 \, J/g$. If the work done in the process of expansion of $1 \, g$ of water is $168 \, J$,then the increase in internal energy is ....... $J$.

$1 \, kg$ of a gas does $20 \, kJ$ of work and receives $16 \, kJ$ of heat when it is expanded between two states. $A$ second kind of expansion can be found between the initial and final states which requires a heat input of $9 \, kJ$. The work done by the gas in the second expansion is ....... $kJ$.