For a reaction,$A_{(g)} \to A_{(l)}$; $\Delta H = -3RT$. The correct statement for the reaction is

Which of the following statements regarding the first law of thermodynamics is correct?

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?

$A$ gas can be taken from state $A$ to state $B$ via two different paths $ACB$ and $ADB$. When path $ACB$ is used, $60 \text{ J}$ of heat flows into the system and $30 \text{ J}$ of work is done by the system. If path $ADB$ is used, the work done by the system is $10 \text{ J}$. The heat flow into the system in path $ADB$ is: (in $text{ J}$)

For the reaction $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$ at constant temperature and pressure,if $\Delta H$ and $\Delta U$ are the enthalpy and internal energy changes for the reaction,which of the following equations is correct?

$A$ gas expands against a variable pressure given by $P = \frac{20}{V}$ ($P$ in $atm$ and $V$ in $L$). During expansion from volume of $1 \ L$ to $10 \ L$,the gas undergoes an increase in internal energy of $400 \ J$. How much heat is absorbed by gas during expansion (in $J$)? (Given: $1 \ L \cdot atm = 101.3 \ J$)