CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 6 - MCQExams.com

For the reaction,
$${ Br }_{ 2 }(l)+{ Cl }_{ 2 }(g)\longrightarrow 2BrCl(g)$$
$$\Delta H=29.37kJ\quad { mol }^{ -1 };\Delta S=104J\quad { mol }^{ -1 }$$. Find the temperature above which the reaction would become spontaneous.
  • Above $$273.4\ K$$
  • Above $$283.4\ K$$
  • Above $$282.4\ K$$
  • Above $$373.4\ K$$
Ideal gas is contained in a thermally insulated and rigid container and it is heated through a resistance $$100\Omega $$ by passing a current of $$1A$$ for five minutes, then change in internal energy of the gas is
  • $$0kJ$$
  • $$30kJ$$
  • $$10kJ$$
  • $$20kJ$$
Which of the following is a feasible reaction?
  • $$Ba(s)+{ K }_{ 2 }{ SO }_{ 4 }(aq)\rightarrow Ba{ SO }_{ 4 }(aq+2K(s)$$
  • $$Zn(s)+2Ag{ NO }_{ 3 }(aq)\rightarrow Zn{ \left( { NO }_{ 3 } \right) }_{ 2 }(aq)+2Ag(s)\quad $$
  • $$Mg(s)+{ Na }_{ 2 }{ SO }_{ 4 }(aq)\rightarrow Mg{ SO }_{ 4 }(aq)+2Na(s)\quad $$
  • $$Cu(s)+Mg{ SO }_{ 4 }(aq)\rightarrow Cu{ SO }_{ 4 }(aq)+Mg(s)$$
Heat of combustion $$\Delta H^o$$ for $$C(s), H_2(g)$$ and $$CH_4(g)$$ are $$-94,-68$$ and $$-213 kcal/mol$$ respectively. Then $$\Delta H^o$$  for $$C(s) + 2H_2(g) \rightarrow CH_4$$ is:
  • $$-17\, kcal/mol$$
  • $$-111\, kcal/mol$$
  • $$-170\, kcal/mol$$
  • $$-85\, kcal/mol$$
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?
  • Exothermic and decreasing disorder
  • Endothermic and increasing disorder
  • Exothermic and increasing disorder
  • Endothermic and decreasing disorder
Heat is supplied to a certain homogeneous sample of matter, at a uniform rate. Its temperature is plotted against time, as shown. Which of the following conclusions can be drawn? . 
667051_206334eca947437e9815fd7bcdfae454.png
  • Its specific heat capacity is greater in the solid state than in the liquid state.
  • Its specific heat capacity is smaller in the solid state than in the liquid state.
  • Its latent heat of vaporization is greater than its latent heat of fusion.
  • Its latent heat of vaporization is smaller than its latent heat of fusion.
Match the List-II ans List-II and List III:
List-IList-IIList-III
A. $$\Delta \, G>0$$X. $$\Delta \, S>0$$Non-spontaneous
B. $$\Delta \, G<0$$Y. $$\Delta \, S<0$$Spontaneous
C. $$\Delta \, G=0$$Z. $$\Delta \, S=0$$Equilibrium
select the correct answering from the following codes:
  • A-(Y, 1) B-(X, Y) C-(Z, 3)
  • A-(X, 2) B-(Y, 3) C-(Z, 1)
  • A-(X, 3) B-(Y, 1) C-(Z, 2)
  • A-(Y, 1) B-(X, 3) C-(Z, 2)
One mole of a real gas is subjected to a process from $$(2\ bar, 30\ lit, 300\ K)$$ to $$(2\ bar, 50\ lit, 400\ K)$$
Given: $$C_{V} = 40\ J/mol\ K$$,
$$C_{P} = 50\ J/mol/ K$$
Calculate $$\Delta U$$.
  • $$4000\ J$$
  • $$2000\ J$$
  • $$1000\ J$$
  • $$5000\ J$$
Consider the reaction at $$300\ K$$, $$H_{2}(g) + Cl_{2}(g)\rightarrow 2HCl(g), \ \ \ \Delta H^{\circ} = -185\ kJ$$
If $$3$$ mole of $$H_{2}$$ completely reacts with $$3$$ mole of $$Cl_{2}$$ to form $$HCl$$, What is $$\Delta U^{\circ}$$ for this reaction?
  • $$0$$
  • $$-185\ kJ$$
  • $$555\ kJ$$
  • None of these
$${ H }_{ 2 }\left( g \right) +\dfrac { 1 }{ 2 } { O }_{ 2 }\left( g \right) \longrightarrow { H }_{ 2 }O\left( l \right)$$
$${ H }_{ 2 }O\left( l \right) \longrightarrow { H }_{ 2 }O\left( g \right); \Delta H={ x }_{ 4 }$$
Given,
$${ E }_{ H-H }={ x }_{ 1 }$$
$${ E }_{ O-O }={ x }_{ 2 }$$
$${ E }_{ O-H }={ x }_{ 3 }$$
$$\Delta { H }_{ F }$$ of $${ H }_{ 2 }O$$ vapour is:
  • $${ x }_{ 1 }+\dfrac { { x }_{ 2 } }{ 2 } -{ x }_{ 3 }+{ x }_{ 4 }$$
  • $$2{ x }_{ 3 }-{ x }_{ 1 }-\dfrac { { x }_{ 2 } }{ 2 } -{ x }_{ 4 }$$
  • $${ x }_{ 1 }+\dfrac { { x }_{ 2 } }{ 2 } -2{ x }_{ 3 }-{ x }_{ 4 }$$
  • $${ x }_{ 1 }+\dfrac { { x }_{ 2 } }{ 2 } -2{ x }_{ 3 }+{ x }_{ 4 }$$
What is the heat produced when 4 g of anhydrous solid is added to 50 g of water?
  • 400 kJ
  • 1672 J
  • 200 kJ
  • 836 kJ
If $$\triangle H_{vaporisation}$$ of substance $$X(l)$$ (molar mass: $$30\ g/mol)$$ is $$300\ J/g$$ at it's boiling point $$300\ K$$, then molar entropy change for reversible condensation process is____________.
  • $$30\ J/mol.K$$
  • $$-300\ J/mol.K$$
  • $$-30\ J/mol.K$$
  • None of these
At $$27 C$$ the reaction,
$${ C }_{ 6 }{ H }_{ 6\left( g \right)  }\ +\ { 15 }/{ 2\ { O }_{ 2\left( g \right)  } }\longrightarrow 6C{ O }_{ 2\left( g \right)  }\ +\ 3{ H }_{ 2 }{ O }_{ \left( l \right)  }$$
proceeds spontaneously because the magnitude of__________.
  • $$\Delta H=T\Delta S$$
  • $$\Delta H>T\Delta S$$
  • $$\Delta H < T \Delta S$$
  • $$\Delta H>0$$ and $$T\Delta S<0$$
The equilibrium constant of a reaction at $$298K$$ is $$5\times {10}^{-3}$$ and at $$1000K$$ is $$2\times {10}^{-5}$$. What is the sign of $$\Delta H$$ for the reaction?
  • $$\Delta H$$ is +ve
  • $$\Delta H$$ is -ve
  • $$\Delta H\propto 0$$
  • $$\Delta H$$ is $$\pm$$ve
$$\Delta$$G is the net energy available to do useful work and is a measure of free energy. If a reaction has positive enthalpy change and positive entropy change, under what conditions will the reaction be spontaneous?
  • $$\Delta$$G will be positive at low temperature hence reaction is spontaneous at low temperature.
  • $$\Delta$$G will be negative at high temperature hence reaction is spontaneous at high temperature.
  • $$\Delta$$G will be negative at low temperature hence reaction is spontaneous at low temperature.
  • $$\Delta$$G will be negative at all temperature hence reaction is spontaneous at all temperatures.
 $$H_{2(g)} + \dfrac{1}{2} O_{2(g)} \rightarrow H_2O_{(g)}$$$$\Delta H = 241.8 kJ$$ $$CO_{(g)} + \dfrac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$$ $$\Delta H = 283 kJ$$ 
The heat evolved during the combustion of $$112$$ litre of water gas (mixture of equal volume of $${H}_{2}$$ and $$CO$$) is:
  • $$241.8kJ$$
  • $$283kJ$$
  • $$1312kJ$$
  • $$1586kJ$$
The specific heat of a gas is found to be $$0.075$$ calories at constant volume and its formula weight is $$40$$. The atomicity of the gas would be:
  • one
  • two
  • three
  • four
A piston cylinder device initially contains $$0.2m^3$$ neon (assume ideal) at 200 kPa inside at $$T_1 ^0C$$. A value is now opened and neon is allowed to escape until the volume reduces to half the initial volume. At the same time heat transfer with outside at $$T_2 ^0C$$  ensures a constant temperature inside. Select the statement(s) for given process :
759209_981c52a6d3114f638eea2be315423ce3.png
  • $$\Delta U$$ must be zero
  • $$\Delta U$$ may not be zero
  • q may be +ve
  • q may not be -ve
Hess's law is applicable for the determination of heat of ________.
  • transition
  • formation
  • reaction
  • all of these.
$$Al^{3+} (aq) + 3e^{-}\rightarrow Al(s); E^{\circ} = -1.66\ V$$
$$Cu^{2+} (aq) + 2e^{-}\rightarrow Cu(s); E^{\circ} = + 0.34\ V$$
What voltage is produced under standard conditions to give a spontaneous reactions by combination of these two-half cells?
  • $$1.32\ V$$
  • $$-1.32\ v$$
  • $$2.00\ V$$
  • $$-2.00\ V$$
Supposing the distance between the atoms of a diatomic gas to be constant, its specific heat at constant volume per mole(gram mole) is?
  • $$\frac{5}{2}R$$
  • $$\frac{3}{2}R$$
  • R
  • $$\frac{7}{2}R$$
Which of the following statement(s) is/are true?
"Internal energy of an ideal gas ............"
  • Decreases in an isobaric process
  • Remains constant in an isothermal process
  • Increases in an isobaric process
  • Decreases in an isobaric expansion
A reaction proceeds through two paths I and II to convert $$X$$ $$\rightarrow$$ $$Z$$. What is the correct relationship between $$Q$$, $$Q_1$$ and $$Q_2$$ ($$Q$$ represents a change in internal energy, here) ?
925698_88265b537ec54f58915b6f4ae9f75c45.png
  • $$Q = Q_1 \times Q_2$$
  • $$Q = Q_1 + Q_2$$
  • $$Q = Q_2 - Q_1$$
  • $$Q = Q_1 / Q_2$$
The value of $$\Delta E$$ for combustion of 16 g of $$CH_4$$ is -885389 J at 298 K. The $$\Delta H$$ combustion for $$CH_4$$ in J $$mol^{-1}$$ at this temperature will be: $$(Given that, R \, = \, 8.314 \, JK^{-1} \, mol^{-1})$$
  • $$-55337$$
  • $$-880430$$
  • $$-885389$$
  • $$-890348$$
The statement "The change of enthalpy of a chemical reaction is same whether the reaction takes place in one or several steps" is:
  • Le Chatelier's law
  • van't Hoff's law
  • first law of thermodynamics
  • Hess's law.
$$C_2H_6(g) + \frac{7}{2}O_2(g) \rightarrow 2CO_2 (g) + 3H_2O(l)$$
$$\delta E - \delta H$$ for this reaction $$27^0$$C will be :
  • $$ + 1247.1$$J
  • $$ - 1247.1$$J
  • $$ -6235.5$$J
  • $$ +6235.5$$J
For the reaction at $$\ { 25 }^{ o }C,{ X }_{ 2 }{ O }_{ 4(l) }\longrightarrow 2X{ O }_{ 2(g) }\quad $$
$$\Delta H=2.1kcal$$ and $$\Delta S=20cal\quad { K }^{ -1 }$$. 
The reaction would be:
  • spontaneous
  • non-spontaneous
  • at equilibrium
  • unpredictable
The total entropy change ($$\Delta S_{total}$$) for the system and surroundings of a spontaneous process is given by :
  • $$\Delta S_{total} = \Delta S_{system} + \Delta S_{surr} > 0$$
  • $$\Delta S_{total} = \Delta S_{system} + \Delta S_{surr} < 0$$
  • $$\Delta S_{system} = \Delta S_{total} + \Delta S_{surr} > 0$$
  • $$\Delta S_{surr} = \Delta S_{total} + \Delta S_{system} < 0$$
For a reaction to be spontaneous at any temperature, the conditions are:
  • $$\Delta$$ H = +ve, $$\Delta$$ S = +ve
  • $$\Delta$$ H = -ve, $$\Delta$$ S = -ve
  • $$\Delta$$ H = +ve, $$\Delta$$ S = -ve
  • $$\Delta$$ H = -ve, $$\Delta$$ S = +ve
Which of the following statements is not correct?
  • For a spontaneous process, $$\Delta G$$ must be negative.
  • Enthalpy, entropy, free energy etc. are state variables.
  • A spontaneous process is reversible in nature.
  • Total of all possible kinds of energy of a system is called its internal energy.
The volume of gas is reduced to half from its original volume. The specific heat will:
  • get reduced to half
  • get doubled
  • remains constant
  • get increased by four times
1 mole of an ideal gas STP is subjected to a reversible adiabatic expansion to double its volume. The change in internal energy $$(\gamma = 1.4)$$ 
  • 1169 J
  • 769 J
  • 1373 J
  • 969 J
Internal energy of an ideal gas depends upon
  • temperature only
  • volume only
  • both volume and temperature
  • neither volume nor temperature
Three stars A, B, C have surface temperatures $$T_A$$, $$T_B$$ and $$T_C$$. A appears bluish, B appears reddish and C appears yellowish. We can conclude that:
  • $$T_A > T_C > T_B$$
  • $$T_A > T_B > T_C$$
  • $$T_B > T_C > T_A$$
  • $$T_C > T_B > T_A$$
The signs of $$\Delta$$H, $$\Delta$$S and $$\Delta$$G for a non-spontaneous reaction at all temperatures would be:
  • +,+,-
  • +,-,+
  • -,-,-
  • +,+, +
1 kg of water is heated from 40 C to 70 C, If its volume remains constant, then the change in internal energy is (specific heat of water = 4148 J$${ kg }^{ -1 }{ K }^{ -1 })$$
  • $$2.44\times { 10 }^{ 5 }$$J
  • $$1.62\times { 10 }^{ 5 }$$J
  • $$1.24\times { 10 }^{ 5 }$$J
  • $$2.62\times { 10 }^{ 5 }$$J
An electric heater supplies heat to a system at a rate of 120 W. If system performs work at a rate of 80 J $${ s }^{ -1 }$$, the rate of increase in internal energy is :
  • 30 J $${ s }^{ -1 }$$
  • 40 J $${ s }^{ -1 }$$
  • 50 J $${ s }^{ -1 }$$
  • 60 J $${ s }^{ -1 }$$
An ideal gas undergoing a change of state from A  to  B  through   four  different  paths  I,   II   ,III  and   IV  as  shown  in  the  P-V  diagram  that   lead  to  the  same  change of state, then the change in internal energy is
941808_5e621636679e401c9c401d1d61995da1.png
  • Same in I and II but not in III and IV
  • Same in III and IV but not in I and II
  • Same in I,II and III but not in IV
  • Same in all of the four cases
The signs of $$\triangle$$ H, $$\triangle$$ S and $$\triangle$$ G for a non-spontaneous reaction at all temperatures would be:
  • +, +, -
  • +, -, +
  • -, -, -
  • +, +, +
Two bars of same length and same cross -sectional area but of different thermal conductivities $$K_1$$ and $$K_2$$ are joined end to end as shown in the figure .One end of the compound bar is at temperature $$T_1$$ and the opposite end at temperature $$T_2$$ $$(where T_1 > T_2)$$.
The temperature of the junction is 
953349_f4f7ed46e4444215ad14cde1bd85a5c0.png
  • $$\dfrac{K_1T_1+K_2T_2}{K_1+K_2}$$
  • $$\dfrac{K_1T_2+K_2T_1}{K_1+K_2}$$
  • $$\dfrac{K_1(T_1+T_2)}{K_2}$$
  • $$\dfrac{K_2(T_1+T_2)}{K_1}$$
A certain mass of gas is taken from an initial thermodynamic state A to another state B by process I and II. In process I the gas does 5 joules of work and absorbs 4 joules of heat energy. In process II, the gas absorbs 5 joules of heat. The work done by the gas in process II (see figure) is
992232_5b8b47efd9a74771b9616088c7521c05.png
  • +6 joules
  • -6 joules
  • +4 joules
  • -4 joules
For the combustion of $$CH_4$$ at 1 atm pressure & 300 K, which of the following options is correct?
$$2M + O_2 \xrightarrow  2MO$$
$$\Delta G_{1000 ^{\circ}C} = -921 kJ/mol$$
$$\Delta G_{1900 ^{\circ}C} = -300 kJ/mol$$
$$2C + O_2 \xrightarrow 2CO$$
$$\Delta G _{1000 ^{\circ}C} = -432 kJ/mol$$
$$\Delta G_{1900 ^{\circ}C} = -624 kJ/mol$$
$$MO + C \xrightarrow{\Delta} M + CO \uparrow$$
This reaction is feasible at temperature:
  • $$1900^\circ C$$
  • $$1000^\circ C$$
  • $$900^\circ C$$
  • $$1200^\circ C$$
Which of the following parameters does not charaterize the thermodynamic state of matter?
  • temperature
  • pressure
  • work
  • volume
The internal energy $$U$$ is a unique function of any state because change in $$U$$.
  • Does not depends upon path
  • Depends upon path
  • Corresponds to adiabatic process
  • Corresponds to an isothermal process
One end of a $$0.25\ m$$ long metal bar is in steam and the other end is in contact with ice. If $$12\ g$$ of ice melts per minute, what is the thermal conductivity of the metal? Given cross-section of the bar $$= 5\times 10^{-4} m^{2}$$ and latent heat of ice is $$80\ cal/g$$.
  • $$80\ cal/s-m-^{\circ}C$$
  • $$90\ cal/s-m-^{\circ}C$$
  • $$70\ cal/s-m-^{\circ}C$$
  • $$60\ cal/s-m-^{\circ}C$$
If for a reaction $${k_c}$$ = 1 then $$\Delta G^\circ $$=________.
  • 1.987
  • 4.184
  • 0
  • 1
"Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a statement of the consequence of
  • second law of thermodynamics
  • conservation of momentum
  • conservation of mass
  • first law of thermodynamics
Select the incorrect option about spontaneous exothermic reaction.
  • $$\Delta S_{Surr} = + ve$$
  • $$\Delta S_{Overall} = + ve$$
  • $$\Delta S_{System} = - ve$$
  • $$\Delta S_{System}= + ve$$ always
The internal energy of a system remains constant when it undergoes
  • Cyclic process
  • An isothermal process
  • Any process in which the heat given out by the system is equal to work done on the system
  • All of the above
Which of the following options is correct regarding spontaneity of a process occurring on a system in which only pressure-volume? work is involved and S, G, Cl, H, V, and P have usual meaning as in thermodynamics?
  • $$(dG)_{U, V} < 0, (dS)_{T, V} > 0$$
  • $$(dH)_{S, V} < 0, (dG)_{T, P} < 0$$
  • $$(dU)_{S, V} < 0, (dG)_{T, V} < 0$$
  • $$(dS)_{H, P} > 0, (dG)_{T, P} < 0$$
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