In the $p-V$ diagram below, the dashed curved line is an adiabat.For a process that is described by a straight line joining two points $X$ and $Y$ on the adiabat (solid line in the diagram) heat is (Hint consider the variation in temperature from $X$ to $Y$ along the straight line)

An ideal gas expands from volume $V_1$ to $V_2$. This may be achieved by either of the three processes: isobaric, isothermal and adiabatic. Let $\Delta U$ be the change in internal energy of the gas, $Q$ be the quantity of heat added to the system and $W$ be the work done by the system on the gas. Identify which of the following statements is false for $\Delta U$?

A thermodynamic system is taken from an original state $D$ to an intermediate state $E$ by the linear process shown in the figure. Its volume is then reduced to the original volume from $E$ to $F$ by an isobaric process. The total work done by the gas from $D$ to $E$ to $F$ will be $……J$

In the figure shown, amount of heat supplied to one mole of an ideal gas is plotted on the horizontal axis and amount of work done by gas is drawn on vertical axis. Assuming process be isobaric i.e. gas can be 

A fixed amount of a gas undergoes a thermodynamic process as shown such that heat interaction along path $B \to C \to A$ is equal to the work done by the gas along path $A \to B \to C$. Then process $A \to B$ is :-