Question

Three different processes that can occur in an ideal monoatomic gas are shown in the P vs V diagram. The paths are labelled as $A\to B , A\to C$ and $A \to D$ The change in internal energies during these process are taken as $E _{ AB }, E _{ AC }$ and $E _{ AD }$ and the workdone as $W _{ AB }$ $W _{ AC }$ and $W _{ AD }$ The correct relation between these parameters are:

• A. $E _{ AB }= E _{ AC }= E _{ AD }, W _{ AB } >\, 0, W _{ AC }=0, W _{ AD }>\,0$
• B. $E _{ AB }<\, E _{ AC }< \,E _{ AD }, W _{ AB }\,>0, W _{ AC } > \,W _{ AD }$
• C. $E _{ AB }= E _{ AC }<\, E _{ AD }, W _{ AB } >\,0, W _{ AC }=0, W _{ AD }<\, 0$
• D. $E _{ AB }>\, E _{ AC }>\, E _{ AD }, W _{ AB }<\, W _{ AC }<\, W _{ AD }$

Answer 1

Answer: (A)

$\Delta U = nC _{ v } \,\Delta T =$ same
$AB \to $ volume is increasing $\Rightarrow W >\,0$
$AD \to $ volume is decreasing $\Rightarrow W <\,0$
$AC\to $ volume is constant $\Rightarrow W =0$