Heat and Work

Q. Which of the following statements is false?

1. Work done during a reversible process is zero
2. Work and heat are path functions
3. Work done during a cyclic process is zero
4. When a gas expands in vaccum, it does not perform any work

Q. When a system is taken from A to C through path ABC, 10 J of heat flows to the system and 4 J of work is done by the system.How much heat flows into the system in path ADC, if the work done by the system is 3 J?

Q. 1 mole of an ideal gas, initially at 400 K and 10 atm is first expanded at constant pressure till the volume is doubled. Then the gas is made to undergo an isochoric process, in which its temperature is found to decrease. In the last step, the gas was compressed reversibly and adiabatically to its initial state. Determine the net work involved in this cyclic process (in terms of R). Given, $C_V$ for gas $=1.5\text{R},(4{)}^{-1/3}=0.63$. If $|W|=\text{2 R}\times \text{z}$, what is the value of $\text{z}$?

Q. For the given graph, which parameters will be non-zero?

1. ∆H
2. ∆U
3. ∆S
4. Q

Q. One mole each of $Ca{C}_2,A{l}_4{C}_{3}andM{g}_2{C}_3$ react with $H_{2}O$ in separate open flasks at ${25}^{o}C.$ Numerical value of the work done by the system is in the order:
Given reactions:
$Ca{C}_2\left(s\right)+2H_{2}O\left(l\right)\to Ca\left(OH{)}_2\right(s)+C_2{H}_2(g)$
$A{l}_4{C}_3\left(s\right)+12H_{2}O\left(l\right)\to 4Al\left(OH{)}_3\right(s)+3C{H}_4(g)$
$M{g}_2{C}_3\left(s\right)+4H_{2}O\left(l\right)\to 2Mg\left(OH{)}_2\right(s)+C{H}_3-C\equiv CH(g)$

1. $Ca{C}_2<A{l}_4{C}_3<M{g}_2{C}_3$
2. $Ca{C}_2=M{g}_2{C}_3<A{l}_4{C}_3$
3. $Ca{C}_2<M{g}_2{C}_3<A{l}_4{C}_3$
4. $Ca{C}_2>A{l}_4{C}_3>M{g}_2{C}_3$

Q. A thermodynamic system goes from states (i) $P_1,V$ to $2P_1,V$ and
$\left(ii\right)P,V_{1}toP,2V_1$
The work done in the two cases respectively is:

1. Zero, Zero
2. Zero, $-P{V}_1$
3. $-P{V}_1,-P_1{V}_1$
4. $-P{V}_1,$ Zero

Q. $56\text{g}$ of iron reacts with dilute $H_{2}S{O}_4$ at $30{}^o\text{C}$. Work done (in cal) in:
$\left(I\right)$ a closed vessel of fixed volume
$\left(II\right)$ an open vessel
is:
(given molar mass of $Fe$ is $56\text{g/mol}$)

1. $\begin{array}{cc}I& II\\ 0& -606\end{array}$
2. $\begin{array}{cc}I& II\\ 0& 0\end{array}$
3. $\begin{array}{cc}I& II\\ -600& 600\end{array}$
4. $\begin{array}{cc}I& II\\ 0& -303\end{array}$

Q. In the figure , the net amount of work done will be:

1. Positive
2. Negative
3. Zero
4. Infinity

Q. Assign the sign of work done (based on SI convention) in the following chemical changes taking place against the external atmospheric pressure:
$\left(I\right)N_2\left(g\right)+3H_2\left(g\right)\to 2N{H}_3\left(g\right)$
$\left(II\right)N{H}_{4}HS\left(s\right)\to N{H}_3\left(g\right)+H_{2}S\left(g\right)$
$\left(III\right)C\left(s\right)+C{O}_2\left(g\right)\to 2CO\left(g\right)$
$\left(IV\right)C_2{H}_6\left(g\right)+3.5O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(l\right)$

1. I II III IV
   $+--+$
2. I II III IV
   $++--$
3. I II III IV
   $-+0+$
4. I II III IV
   $+-0-$

Q. Identify the pair of intensive properties among the following.

1. Enthalpy and temperature
2. Volume and temperature
3. Enthalpy and volume
4. Temperature and refractive index