When a system expands under adiabatic conditions,what happens to its internal energy?

When $100 \ cal$ of heat is supplied to a system,the work done by the system is $300 \ J$. The change in internal energy of the system is ..... $J$.

$A$ gas absorbs $100 \ J$ of heat and is simultaneously compressed by a constant external pressure of $1.5 \ atm$ from a volume of $8.0 \ L$ to $2.0 \ L$. The change in internal energy for the gas in Joules is $(1 \ L \cdot atm = 101.32 \ J)$.

During the melting of an ice slab at $273 \ K$ and $1 \ atm$ pressure:

Which one of the following is applicable for an adiabatic expansion of an ideal gas?

$A$ gas expands isothermally from $10 \, dm^3$ to $20 \, dm^3$ at a constant external pressure of $1 \, atm$. If it absorbs $800 \, J$ of heat from the surroundings,what is the value of $\Delta U$ in $J$ for this process?