If a gas expands adiabatically from $1 \, L$ to $12 \, L$ against a constant external pressure of $0.75 \, atm$,the $\Delta U$ of the gas is .... $J$. (in $.9$)

Express the change in internal energy of a system when
$(i)$ No heat is absorbed by the system from the surroundings,but work $(w)$ is done on the system. What type of wall does the system have?
$(ii)$ No work is done on the system,but $q$ amount of heat is taken out from the system and given to the surroundings. What type of wall does the system have?
$(iii)$ $w$ amount of work is done by the system and $q$ amount of heat is supplied to the system. What type of system would it be?

For the reaction,$N_{2(g)} + 3 H_{2(g)} \rightarrow 2 NH_{3(g)}$,$\Delta H$ is equal to

$A$ 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 $(1 \ L \cdot atm = 101.32 \ J)$.

The change in internal energy equals

$A$ system is provided with $50 \ J$ of heat and the work done on the system is $10 \ J$. What is the change in internal energy of the system in joules?