Internal Energy

Q. The internal energy (U) of an ideal gas is plotted against volume for a cyclic process ABCDA, as shown in the figure.
The temperature of the gas at B and C are $500K$ and $300K$, respectively. The heat absorbed by the gas (in cal/mol) in this cyclic process, is :

Q.

Define Quantisation of energy.

Q. One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively. Choose the correct statement:

1. The change in internal energy in the process AB is -350 R.
2. The change in internal energy in whole cyclic process is 250 R.
3. The change in internal energy in the process BC is -500 R.
4. The change in internal energy in the process CA is 700 R.

Q. The maximum efficiency of a heat engine operating between ${100}^{o}C$ and ${25}^{o}C$ is

1. 20.11%
2. 22.2%
3. 25.17%
4. None

Q. The standard enthalpies of formation of $A{l}_2{O}_3$ and $CaO$ are $-1675kJmo{l}^{-1}$ and $-635kJmo{l}^{-1}$ respectively.
For the reaction,
$3CaO+2Al\to 3Ca+A{l}_2{O}_3$ the standard reaction enthalpy, ${\Delta }_r{H}^0$=______kJ (Rounded off to the Nearest Integer).

Q. 1 gram sample of $N{H}_{4}N{O}_3$ is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by 6.12 K. The heat capacity of the system is 1.23 kJ/g-deg. What is the molar heat of decomposition for $N{H}_{4}N{O}_3$?

1. $7.53kJ/mol$
2. $-398.1kJ/mol$
3. $-16.1kJ/mol$
4. $602kJ/mol$

Q. When 1 moe of ice melts at $0^{o}C$ and at constant pressure of 1 atm, 1440 calories of heat are absorbed by the system. The molar volume of ice and water are 0.0196 and 0.0180 litre respectively. Which of the following is correct?

1. $\Delta U\approx \Delta H$
2. $\Delta U=1548cal$
3. $\Delta U=1056cal$
4. None of the above

Q. If 500 calorie of heat energy is added to a system and the system does 350 calorie of work on the surroundings, the energy change of the system is:

1. -150 cal
2. 850 cal
3. -850 cal
4. 150 cal

Q.

One litre of a mixture of carbon monoxide and carbon dioxide is passed through a tube containing red hot charcoal , the volume now becomes 1.6 litres. Volumes are measured under similar conditions. Find out the composition of gaseous mixture.

Q.

A sample of ideal gas ($\gamma$ = $1.4$) is heated at constant pressure. If $140J$ of heat is supplied to gas, find $\Delta U$ and $w$.

1. 60 J, -80 J

2. -50 J, 60 J

3. None of these

4. 50 J, -60 J

Q. Express the rate for the following reaction in terms of concentration of reactants and products.
$H_2\left(g\right)+I_2\left(g\right)\to 2HI\left(g\right)$.

Q. Two mole of ideal diatomic gas $(C_{v,m}=5/2R)$ at $300K$ and $10atm$ expanded irreversibly and adiabatically to a final pressure of $2atm$ against a constant pressure of 1 atm. Calculate change in internal energy $△U$

1. $-2164.1J$
2. $-1052.1J$
3. $-1662.8J$
4. $864.28J$

Q. A gas occupies $2litre$ at STP. It is provided with $58.63J$ of heat so that its volume becomes $2.5litre$ at $1atm$. Calculate the change in its internal energy (in $J$).

1. 8.6
2. 10
3. 15.8
4. 11.5

Q. According to the following figure, the magnitude of the enthalpy change of the reaction
$A+B\to M+NinkJ{\text{mol}}^1$
is equal to . (Integer answer)

Q.

A gas at $50°\mathrm{C}$ constant pressure and a constant pressure requires the heat $160\mathrm{calories}$ to raise the temperature. The same mass of gas requires $100°\mathrm{C}$ a constant volume and $240\mathrm{calories}$ heat is released. Degrees of freedom does each molecule of this gas have? (Assume that gas is ideal)

1. $7$

2. $5$

3. $6$

4. $3$

Q. The standard enthalpies of formation at 300 K for $CC{l}_4\left(l\right),H_{2}O\left(g\right),C{O}_2\left(g\right)andHCl\left(g\right)are-107,-242,-394and-93kJmo{l}^{-1},$ respectively. The value of $△U_{300}^o$ for the reaction:

$CC{l}_4\left(l\right)+2H_{2}O\left(g\right)\to C{O}_2\left(g\right)+4HCl\left(g\right)$ is
$-xkJmo{l}^{-1}$. Find the value of $x$
(Take $R=8.314J{K}^{-1}mo{l}^{-1}$)

Q. Two moles of an ideal monoatomic gas occupies a volume V at $27{}^{\circ }C$. The gas expands adiabatically to a volume 2V. Calculate (a) the final temperature of the gas and (b) change in its internal energy.

1. (a) 189 K (b) 2.7 kJ
2. (a) 295 K (b) - 2.7 kJ
3. (a) 189 K (b) -2.7 kJ
4. (a) 295 K (b) 2.7 kJ

Q.

The internal energy change when a ssyste goes from state A TO B is 40kJ/mol.If the system goes from A to by a reversible path and returns to state A by an irreversible path what would be the change in internal energy

Q.

An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joules per second. At what rate is the internal energy increasing?

Q.

Does entropy increase in an open system?

Q. The value of $\Delta H-\Delta U$ for the following reaction at ${37}^o$ C will be
$2N{H}_3\left(g\right)\to N_2\left(g\right)+3H_2\left(g\right)$

1. $51.54{\text{J mol}}^{-1}$
2. $-51.54{\text{J mol}}^{-1}$
3. $51.54{\text{kJ mol}}^{-1}$
4. $5.154{\text{kJ mol}}^{-1}$

Q. A gas sample is cooled and loses 65 J of heat. The gas contracts as it cools and work done on the system equal to 20 J. What are q, w and $△U$ ?

1. $q=-65J,w=20J,△U=-45J$
2. $q=-70J,w=10J,△U=35J$
3. $q=65J,w=10J,△U=-35J$
4. $q=65J,w=20J,△U=45J$

Q. If the ratio of specific heat of a gas at constant pressure to that at constant volume is $\gamma ,$ the change in internal energy of a mass of gas, when the volume changes from $V$ to $3V$ under constant pressure $P$, is

1. $\frac{R}{(\gamma -1)}$
2. $PV$
3. $\frac{\gamma PV}{\gamma -1}$
4. $\frac{2PV}{\gamma -1}$

Q. A system is changed from state A to state B by one path and from B to A by another path. If $△U_1$ and $△U_2$ are the corresponding changes in internal energy, then:-

1. $△U_1+U_2=+ve$
2. $△U_1+U_2=-ve$
3. $△U_1+U_2=0$
4. None of the above

Q. The internal energy of an ideal gas:

1. increases with increase in temperature
2. remains unaffected with temperature
3. decreases with increase in temperature
4. can be calculated by the reaction, $E=m{c}^2$

Q.

Which of the following statements is correct for the reaction $CO\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\to C{O}_2\left(g\right)$ at constant temperature and pressure?

1. None of these

2. 

3. 

4. 

Q. Internal energy is an example of

1. None of these
2. Path function
3. State function
4. Both (a) and (b)

Q. One gram of ice (at $0^{o}C$) is mixed with one gram of steam (at ${100}^{o}C$). After thermal equilibrium, the temperature of the mixture is

1. $0^{o}C$
2. ${100}^{o}C$
3. ${55}^{o}C$
4. ${80}^{o}C$

Q.

Is entropy a function of time?

Q. When an iron rod is heated in a furnace, the colour of the iron rod first turns dull red and on further increase in temperature it changes to bright red to orange, then yellow, progressively white and then finally blue at the elevated temperatures.
This sequence of colours observed on heating an iron rod are in the sequence of __________

1. Increasing wavelength
2. Decreasing wavelength
3. Decreasing frequency
4. None of the above