CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 8 - MCQExams.com

$$2{H}_{2(g)}+{O}_{2(g)}\rightarrow 2{H}_{2}{O}_{(l)};\Delta H=-ve$$ and $$\Delta G=-ve$$. Then the reaction is
  • Spontaneous and instantaneous
  • Spontaneous and endothermic
  • Spontaneous and slow
  • Non spontaneous and slow
Answer the question based on the diagram involving $$1$$ mole of ideal gas.
Process $$A\rightarrow B$$ represents:
1135286_a56902c1791f4a0ea2884f6df1e6e601.png
  • isobaric
  • isochoric
  • isothermal
  • adiabatic
In standard state the non spontaneous reaction among the following is:
  • melting of ice
  • natural radioactivity
  • freezing of water
  • rusting of iron
Under which of the following conditions is the relation, $$\Delta H=\Delta E+P\Delta V$$ valid for a system:
  • Constant pressure
  • Constant temperature
  • Constant temperature and pressure
  • Constant temperature, pressure and composition
The heat capacity of 2.0 moles of He gas at constant temperature is (in cal/mol/K)
  • 0
  • 3
  • 8
  • $$\infty $$
For the reaction, $$2A(g)+B(g)\rightarrow 2D(g),\Delta {U}^{o}=-10.5kJ$$ and $$\Delta {S}^{o}=-44.10J{K}^{-1}$$. Calculate $$\Delta {G}^{o}$$ for the reaction and predict whether the reaction may occur spontaneously:
  • $$0.165\ kJ$$, the reaction is not spontaneous.
  • $$0.225\ kJ$$, the reaction is not spontaneous.
  • $$0.164\ kJ$$, the reaction is spontaneous.
  • $$0.225\ kJ$$, the reaction is spontaneous.
Evaporation of water is 
  • An endothermic change
  • An exothermic change
  • A process where no heat change occurs
  • A process accompained by chemical reaction
At $$27C$$ the reaction,
$${ C }_{ 6 }{ { H }_{ 6 } }_{ { (l) } }+\frac { 15 }{ 2 } { { O }_{ 2 } }_{ (g) }\rightarrow { { 6CO }_{ 2 } }_{ (g) }+{ { 3H }_{ 2 }O }_{ (l) }$$
 proceeds spontaneously because the magnitude of?
  • $$\Delta H=T\Delta S$$
  • $$\Delta H>T\Delta S$$
  • $$\Delta H$$<$$T\Delta S$$
  • None of these
For the given reaction
$$H_{2}(g)+S(s)\longrightarrow H_{2}S(g);\ \Delta H_{T}=100\ kJ/mol$$ and $$\Delta S_{T}=400\ J/mol/K$$
Temperature at which above reaction occurs reversibly is (Assuming $$\Delta H_{T}$$ and $$\Delta S_{T}$$ are independent of temperature)
  • $$200\ K$$
  • $$250\ K$$
  • $$400\ K$$
  • $$None$$
A constant volume gas thermometer shows pressure reading of 50 cm and 90 cm of mercury at 0$$^{0}C$$ and 100$$^{0}C$$ respectively. When the pressure reading is 60 cm  of mercury, the temperature is:-
  • 25$$^{0}C$$
  • 40$$^{0}C$$
  • $$^{0}C$$
  • $$30^{0}C$$

A gas occupies $$2L$$ at S.T.P. It is provided with $$300 Joule$$ of heat so that its volume becomes $$2.5 litre$$ at a pressure of $$1 atm$$. The value of $$\Delta U$$(Change in internal energy) of process is :- 
  • $$350.5 Joule$$
  • $$249.5 Joule$$
  • $$150.35 Joule$$
  • None of these
The values of $$\Delta H$$ and $$\Delta S$$  for the reaction, $${ C }_{ \left( graphite \right)  }+{ CO }_{ { 2 }_{ \left( g \right)  } }\longrightarrow { 2CO }_{ \left( g \right)  }$$  are $$170 \ kJ$$ and $$170 \ JK^{-1}$$, respectively. This reaction will be spontaneous at :-
  • $$510 \ K$$
  • $$710 \ K$$
  • $$910 \ K$$
  • $$1110 \ K$$
Among the following the non-spontaneous reaction is :
  • $$ROH+R'MgX \rightarrow R'H+Mg(OR)X$$
  • $$RONa+NH_{3} \rightarrow NaHN_{2}+ROH$$
  • $$RONa+H_{2}O \rightarrow NaOH+ROH$$
  • $$ROH+HC \equiv CNa \rightarrow RONa+HC \equiv CH$$
In a cyclic process, the change in the internal energy of a system over one complete cycle
  • depends on the path
  • is always negative
  • is always zero
  • is always positive
A coffee cup calorimeter initially contains $$125\ g$$ of water, at a temperature of $$24.2^oC$$. $$8\ g$$ of ammonium nitrate $$(NH_4NO_3)$$, also at $$24.2^oC$$, is added to the water and the final temperature is $$18.2^oC$$. What is the heat of solution of ammonium nitrate in $$kJ/mol$$? The specific in capacity of the solution is $$4.2\ J/^oCg$$.
  • $$33.51\ kJ/mol$$
  • $$39.5\ kJ/mol$$
  • $$33.2\ kJ/mol$$
  • $$37.3\ kJ/mol$$
If the temperature difference $$T_1 - T_2$$ is $$120^oC$$. the temperature difference between points A & B is 
1325774_e55b7d2190e5454ebd790a38bacc7cec.png
  • 30
  • 45
  • 60
  • 75
When 250 KJ heat is the system then it does work of 400 KJ then calculate change in internal energy of system ?
  • 650 KJ
  • -650 KJ
  • 200 KJ
  • -200 KJ
1 g of a steam at $$100^{_-^0}C$$ melt how much ice at $$0^{_-^0}C$$? (Latent heat of ice = 80 cal/gm and latent heat of steam = 540 cal/gm)-
  • 1 gm
  • 2 gm
  • 4 gm
  • 8 gm
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
  • $$0^{o}C$$
  • $$100^{o}C$$
  • $$55^{o}C$$
  • $$80^{o}C$$
Which of the following can be calculated from Born-Haber cycle for $$Al_2O_3$$?
  • Lattice energy of $$Al_2O_3$$
  • Electron affinity of O-atom
  • Ionisation energy of Al
  • All of these
Internal energy of an ideal gas depends on:
  • pressure
  • temperature
  • volume
  • none of these
What is the change in entropy when $$2.5 $$ mole of water is heated from $$27^{o}C$$ to $$87^{o}C$$? Assume that the heat capacity is constant $$(C_{p.m}(H_{2}O)=4.2\ J/g-K\ In (1.2)=0.18)$$
  • $$16.6\ J/K$$
  • $$9\ J/K$$
  • $$34.02\ J/K$$
  • $$1.89\ J/K$$
Calculate $${ \Delta  }_{ r }G$$ for the reaction at $$2\mathring { 7\quad  } C$$ :-
$${ H }_{ 2(g) }+2A{ g }_{ (aq) }^{ + }\rightleftharpoons 2A{ g }_{ s }+2{ H }_{ (aq)}^{+} $$
Given : $${ P }_{ { H }_{ 2 } }=0.5$$ bar; $${ [A{ g }^{ + }] }=1{ 0 }^{ -5 }M$$ 
$${ [{ H }^{ + }] }=1{ 0 }^{ -3 }M$$ ; 
$${ \triangle  }_{ r }\mathring { G\quad \quad  } [A{ g }^{ + }]=77.1\quad KJ/mol$$
  • -154.2 KJ/mol
  • -178.9 KJ/mol
  • -129.5 KJ/mol
  • none of these
If $$\Delta G$$ for a reaction is negative, the change is:
  • reversible
  • spontaneous
  • equilibrium
  • non-spontaneous
A vessel contains $$N$$ molecules of a gas at temperature $$T$$. Now the number of molecules is doubled, keeping the total energy in the vessel constant. The temperature of the gas is.
  • $$T$$
  • $$2T$$
  • $$\dfrac{T}{2}$$
  • $$\sqrt 2 T$$
Determine $$ \Delta U^o $$ at 300 K for the following reaction using the listed enthalpies of reaction :
$$ 4CO(g)+8H_{ 2 }(g)\rightarrow 3CH_{ 4 }(g)+CO_{ 2 }(g)+2H_{ 2 }O(I) $$
$$ C (graphite)+1/2O_2(g) \rightarrow CO(g); \Delta H^o_1 = -110.5 kJ $$
$$ CO(g) +1/2 O_2(g) \rightarrow   CO_2(g); \Delta H^o_2 = -282.9 kJ $$
$$ H_2(g) + 1/2 O_2(g) \rightarrow H_2O(I); \Delta H^o_3 = -285.8 kJ $$
$$ C(graphite)+2H_2(g) \rightarrow   CH_4(g); \Delta H^o_4 = -74.8 kJ $$
  • $$-653.5 kJ$$
  • $$-686.2kJ$$
  • $$-747.4kJ$$
  • None of these
For the reaction of one mole of zinc dust with one mole of sulphuric acid in a bomb calorimeter $$\Delta U$$ and w correspond to 
  • $$\Delta U<0,w=0$$
  • $$\Delta U<0,w<0$$
  • $$\Delta U>0,w=0$$
  • $$\Delta U>0,w>0$$
An ideal gas is taken through a cyclic thermo dynamical process through four steps. The amounts of heat involved in steps are
$$Q_1 = 5960 J, Q_2 = -5585 J, Q_3 = -2980 J, Q_4 = 3645 J$$; respectively, the corresponding works involved are $$W_1 = 2200 , W_2 = -825 J, W_3 = -1100 J$$ and $$W_4$$ respectively. Find the value of $$W_4$$ and efficiency of the cycle
  • 1315 J, 10%
  • 765 J, 11%
  • both of them
  • none of these
Assertion : In Free expansion, $$\Delta U = 0$$
Reason : No work is done in free expansion
  • If both assertion and reason are true and reason is the correct explanation of assertion.
  • If both assertion and reason are true but reason is not the correct explanation of assertion.
  • If assertion is true but reason is false.
  • If both assertion and reason are false.
For reversible vaporisation of water at $${\text{10}}{{\text{0}}^{\text{o}}}{\text{C}}$$ and 1 atmospheric pressure, $$\Delta {\text{G}}\;$$ is equal 
  • $$\Delta {\text{H}}\;$$
  • $$\Delta {\text{S}}\;$$
  • zero
  • $$\Delta {\text{H/T}}\;\;$$
$$5$$ mole of ideal gas at $$100K$$ ($${C}_{v,m}=28J/mol/K$$). It is heated upto $$200K$$. Calculate $$\Delta U$$ and $$\Delta (PV)$$ for the process. ($$R=8J/mol-K$$)
  • $$\Delta U=28kJ;\Delta (PV)=8KJ$$
  • $$\Delta U=14kJ;\Delta (PV)=4KJ$$
  • $$\Delta U=14kJ;\Delta (PV)=8KJ$$
  • $$\Delta U=28kJ;\Delta (PV)=4KJ$$
A diatomic ideal gas is expanded at constant at pressure. If work done by the system is $$10 \,J$$ then calculate heat absorbed.
  • $$40 \,J$$
  • $$20 \,J$$
  • $$35 \,J$$
  • $$15 \,J$$
The Normal boiling point of a liquid 'X' is $$400$$ K. Which of the following statement is true about the process $$X(l) \rightarrow X(g)$$?
  • At $$400$$ K and 1 atm pressure $$\Delta G=0$$
  • At $$400$$K and 2 atm pressure $$\Delta G=+ve$$
  • At $$400$$K and 0.1 atm pressure $$\Delta G=-'ve$$
  • At $$410$$K and 1 atm pressure $$\Delta G=+ve$$
For hydrogenation of ethene into ethane  as per following chemical reaction $$CH_2=CH_2+H_2 \xrightarrow[]{Pd} CH_3-CH_3$$
The $$\Delta H_{reaction}$$ is written as
Calculate $$\Delta H_{reaction}$$ for
  • $$\Delta H_{reaction}=4 \Delta H_{C-H}+ \Delta H_{C=C} + \Delta H_{H-H}-6 \Delta H_{H-H}-2 \Delta H_{C-C}$$
  • $$\Delta H_{reaction}=4 \Delta H_{C-H}+ 2\Delta H_{C-C} + \Delta H_{H-H}-6 \Delta H_{C-H}- \Delta H_{C-C}$$
  • $$\Delta H_{reaction}=4 \Delta H_{C-H}+ \Delta H_{C=C} + \Delta H_{H-H}-6 \Delta H_{C-H}- \Delta H_{C-C}$$
  • $$\Delta H_{reaction}= \Delta H_{C-H}+ \Delta H_{C=C} + \Delta H_{H-H}- \Delta H_{C-H}- \Delta H_{C-C}$$
In which process volume increases?
1630580_bf700e2a93cd4d4eba7d34c0cd960207.PNG
  • AB, CD
  • AB, BC
  • CD, DA
  • BC, CD
Which one of the following process is non-spontaneous?
  • Dissolution of $$CuSO_{4}$$ in water
  • Reaction of $$H_{2}$$ and $$O_{2}$$ to form water
  • Water flowing down hill
  • Flow of electric current from low potential to high potential
Hess' Law and bond energy data can be used to calculate the enthalpy change of a reaction. Bromoethane, $$CH_2CH_2Br$$, can be made by reacting ethene with hydrogen bromide.
$$CH_2=CH_2+HBr\rightarrow CH_3CH_2Br$$
What is the enthalpy change for this reaction?
  • $$-674$$ kJ $$mol^{-1}$$
  • $$-64$$ kJ $$mol^{-1}$$
  • $$+186$$ kJ $$mol^{-1}$$
  • $$+346$$ kJ $$mol^{-1}$$
The resultant heat change in a reaction is the same whether it takes
place in one or several stages. This statement is called:
  • Lavoisier and Laplace law
  • Hess's law
  • Joule's law
  • Le-chatelier's principle
An ideal gas undergoes a cyclic process as shown in figure;
$$\Delta u_{BC}=-5 KJ mol^{-1}, q_{AB}= 2 KJ mol^{-1}$$
$$w_{AB}= -5 KJ mol^{-1},W_{CA}=3 KJ mol^{-1}$$
Heat absorbed by the system during process $$CA$$ is

1738935_70e81fa93135482dbc99014a710e4cfc.PNG
  • $$-5 KJ mol^{-1}$$
  • $$+5 KJ mol^{-1}$$
  • $$-18 KJ mol^{-1}$$
  • $$+18 KJ mol^{-1}$$
For which of the following reaction $$\Delta H$$ is equal to $$\Delta u$$?
  • $$ 2HI(g) \leftrightharpoons H_2(g)+I_2(g)$$
  • $$ 2NO_2(g) \leftrightharpoons N_2O_4(g)$$
  • $$N_2(g) + 3H_2(g) \leftrightharpoons 2 NH_3(g)$$
  • $$ 2SO_2(g) +O_2(g) \leftrightharpoons 2SO_3(g)$$
Which statement about reactions that produce heat is not correct?
  • Burning magnesium produces hear energy
  • The overall reaction is exothermic
  • The products have more energy than the reactants
  • The temperature of the surroundings increases
In which case is a reaction possible at any temperature?
  • $$\Delta H < 0, \Delta S > 0$$
  • $$\Delta H < 0, \Delta S > 0$$
  • $$\Delta H < 0, \Delta S > 0$$
  • None of these
Which of the following is the correct equation?
 
  • $$\Delta U=\Delta Q-W$$
  • $$\Delta W=\Delta U+\Delta Q$$
  • $$\Delta U=\Delta W+\Delta Q$$
  • None of these
A gas is expanded from volume $$ V_0$$ and $$2V_0 $$ under three different processes. Process 1 is isobaric, process 2 is isothermal and process 3 is adiabatic . Let $$ \triangle U_1, \triangle U_2 $$ and $$\triangle U_3 $$ be the change in internal energy of the gas in these process. then : 
1739363_cd4598dbbe7145a6aebe550eefa26d33.PNG
  • $$ \triangle U_1 > \triangle U_2 > \triangle U_3 $$
  • $$ \triangle U_1 < \triangle U_2 < \triangle U_3 $$
  • $$ \triangle U_2 < \triangle U_1 < \triangle U_3 $$
  • $$ \triangle U_2 < \triangle U_3 < \triangle U_1 $$
In a reaction $$\Delta H$$ and $$\Delta S$$ both are more than zero. In which of the following cases would the reaction be spontaneous?
  • $$\Delta H > T\Delta S$$
  • $$T\Delta S > \Delta H$$
  • $$\Delta H = T\Delta S$$
  • None of these
Which relation is correct for isochoric process
  • $$\Delta Q=\Delta U$$
  • $$\Delta W=\Delta U$$
  • $$\Delta Q=\Delta W$$
  • None of these
Which of the following endothermic processes are spontaneous?
  • Melting of ice
  • Evaporation of water
  • Heat of combustion
  • Both (a) and (b)
A minus sign of the free energy change denotes that: 
  • The reaction tends to proceed spontaneously
  • The reaction is non spontaneous
  • The system is in equilibrium
  • The reaction is very much unlikely
The spontaneity means, having the potential to proceed without the assistance of external agency. The processes which occur spontaneously are
Note: Two or more options may be correct.
  • flow of heat from colder to warmer body.
  • gas in a container contracting into one comer.
  • gas expanding to fill the available volume.
  • burning carbon in oxygen to give carbon dioxide.
Which of the following
statements is correct?
  • The presence of reacting species in a covered beaker is an example of open system.
  • There is an exchange of energy as well as matter between the system and the surroundings in a closed system.
  • The presence of reactants in a closed vessel made up of copper is an example of a closed system.
  • The presence of reactants in a thermos flask or any other closed insulated vessel is an example of a closed system.
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