# CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 14 - MCQExams.com

 When two mole of an ideal gas $$\left( { C }_{ p.m }=\cfrac { 5 }{ 2 } R \right)$$ heated from $$300K$$ to $$600K$$ at constant pressure. The change in entropy of gas ($$\Delta S$$) is:
• $$-\cfrac{3}{2}R\ln{2}$$
• $$\cfrac{3}{2}R\ln{2}$$
• $$5R\ln {2}$$
• $$\cfrac{5}{2}R\ln{2}$$
 For the reaction$$A\rightleftharpoons B+C$$. At equilibrium, the concentration of $$A$$ is $$1\times { 10 }^{ -3 }M$$ ,$$B$$ is $$0.15M$$ and $$C$$ is $$0.05M$$. The $$\triangle { G }^{ o }$$ for the reaction $$A$$ at $${ 27 }^{ o }C$$ will be
• $$-5kJ/mol$$
• $$-17.3kJ/mol$$
• $$-11.2kJ/mol$$
• $$none\ of\ these$$
 Which of the following is/are correct ?
• $$\Delta H=\Delta U+\Delta$$ (PV) when P and V both changes
• $$\Delta H=\Delta U+P\Delta V$$ when pressure is constant
• $$\Delta H=\Delta U+V\Delta P$$ when volume is constant
• all are correct
 Which of the following processes are spontaneous
• Melting of ice at $$2$$ atm and $$273K$$
• Melting point of ice at $$1/2$$ atm and$$273K$$
• Boiling of water at $$1/2$$ atm and $$373K$$
• Boiling of water at $$2$$ atm and $$373K$$
 For a reaction. $$A(g)\rightarrow A(l);\Delta {H}=-3RT$$. The correct statement for the reaction is:
• $$\left| \Delta H \right| >\left| \Delta U \right|$$
• $$\Delta H=\Delta U\ne 0$$
• $$\left| \Delta H \right| <\left| \Delta U \right|$$
• $$\Delta H=\Delta U= 0$$
 For the spontaneous process $$2F(g)\rightarrow {F}_{2}(g)$$, the sign of $$\Delta H$$ and $$\Delta S$$ respectively are?
• +ve, -ve
• +ve, +ve
• -ve, -ve
• -ve, +ve
 The favourable conditions for a spontaneous reaction are:
• $$T\Delta S> \Delta H, \Delta H=+ve,\Delta S=+ve$$
• $$T\Delta S> \Delta H, \Delta H=+ve,\Delta S=-ve$$
• $$T\Delta S= \Delta H, \Delta H=+ve,\Delta S=-ve$$
• $$T\Delta S= \Delta H, \Delta H=+ve,\Delta S=+ve$$
 For a reaction $${R}_{1},\Delta G=x KJ {mol}^{-1}$$. For a reaction $${R}_{2},\Delta G=y$$ $$KJ{mol}^{-1}$$. Reaction $${R}_{1}$$ is non spontaneous but along with $${R}_{2}$$ it is spontaneous. This means that:
• $$x$$ is $$-ve$$, $$y$$ is $$+ve$$ but in magnitude $$x> y$$
• $$x$$ is $$-ve$$, $$y$$ is $$+ve$$ but in magnitude $$y> x$$
• Both $$x$$ and $$y$$ are $$-ve$$ but not equal
• Both $$x$$ and $$y$$ are $$+ve$$ but not equal
 Which of the following conditions make the process non spontaneous at all temperatures.
• $$\Delta H=+ve;\Delta S=-ve$$
• $$\Delta H=-ve;\Delta S=+ve$$
• $$\Delta H=+ve;\Delta S=+ve$$
• $$\Delta H=-ve;\Delta S=-ve$$
 Consider the formation of $$MgO(s)$$. Assume that $$\triangle { H }^{ o }$$ and $$\triangle { S }^{ o }$$ are independent of temperature:$$Mg(s)+\cfrac { 1 }{ 2 } { O }_{ 2 }\left( g \right) \rightarrow MgO\left( s \right)$$ $$\triangle { H }^{ o }=-602kJ/mol$$, $$\triangle { S }^{ o }=-108kJ/mol$$Calculate $$\triangle { G }$$ for formation of $$MgO(s)$$ at $${0}^{o}C$$ and is the reacion spontaneous or non spontaneous at $${0}^{o}C$$?
• $$29,000 kJ/mol,$$ spontaneous
• $$-29,000 kJ/mol,$$ non spontaneous
• $$-30,000 kJ/mol,$$  spontaneous
• $$30,000 kJ/mol,$$ non spontaneous
 For a spontaneous reaction, the $$\Delta G$$, equilibrium constant, $$K$$ and will be respectively:
• $$-ve,> 1$$
• $$+ve, 1$$
• $$-ve,< 1$$
• $$-ve. 1$$
 For a gaseous reaction,$$A(g)+3B(g)\rightarrow 3C(g)+3D(g)$$$$\Delta E$$ is $$17kcal$$ at $${27}^{o}C$$, assuming $$R=2cal$$ $${K}^{-1}$$ $${mol}^{-1}$$, the value of $$\Delta H$$ for the above reaction is:
• $$15.8kcal$$
• $$18.2kcal$$
• $$20.0kcal$$
• $$16.4kcal$$
 $$\Delta {G}^{o}$$ of $${Cu}_{(aq)}^{+}$$ and $${Cu}_{(aq)}^{2+}$$ respectively are $$+50$$ and $$+66kJ/mole$$. Value of ($$\Delta{H}^{o}-T\Delta {S}^{o}$$) for $${Cu}_{(aq)}^{+}\rightarrow {Cu}_{(aq)}^{2+}$$ in kilo joules is?
• $$-16$$
• $$+116$$
• $$-116$$
• $$+16$$
 Which plot represents for an exothermic reaction:
 Consider the reaction:$$4 NO_{2(g)} + O_{2(g)} \rightarrow 2 N_2O_{5(g)} ; \, \, \, \Delta_rH = -111 kJ$$ If $$N_2O_{5(s)}$$ is formed instead of $$N_2O_{5(g)}$$ in the above reaction, then $$\Delta_rH$$ value will be: [Given, $$\Delta H$$ of sublimation for $$N_2O_5$$ is $$54 \, kJ \, mol^{-1}$$]
• $$+ 54\ kJ$$
• $$+ 219\ kJ$$
• $$-219\ kJ$$
• $$-165\ kJ$$
 $$\Delta{S}_{surroundings}=+959.1J{K}^{-1}{mol}^{-1}$$$$\Delta{S}_{system}=-163.1J{K}^{-1}{mol}^{-1}$$. Then process is?
• Spontaneous
• Non spontaneous
• At equilibrium
• Cannot be predicted from the information
 $$\Delta S$$ for $$4Fe(s)+3{O}_{2}(s)\rightarrow 2{Fe}_{2}{O}_{3}(s)$$ is $$-550J/mol/K$$. The process is found to be spontaneous even at $$298K$$ because  ($$\Delta H=-1650kJ$$)
• $$\Delta {S}_{total}=-2000J$$
• $$\Delta {S}_{total}=+1650J$$
• $$\Delta {S}_{total}=+4980J$$
• $$\Delta {S}_{total}=-4980J$$
 In which of the following case entropy decreases-
• Solid changing to liquid
• Expansion of a gas
• Crystals dissolve
• Polymerisation
 Ethyl chloride ($${C}_{2}{H}_{5}Cl$$) is prepared by reaction of ethylene with hydrogen cloride:$${C}_{2}{H}_{4}(g)+Hcl(g)\rightarrow {C}_{2}{H}_{5}Cl(g)$$; $$\Delta H=-72.3kJ$$What is the value of $$\Delta E$$ (in kJ), if $$70g$$ of ethylene and $$73g$$ of $$HCl$$ are allowed to react at $$300K$$
• $$-69.8$$
• $$-180.75$$
• $$-174.5$$
• $$-139.6$$
 Consider the following processes $$\triangle H(KJ/mol)$$$$\frac { 1 }{ 2 } A\rightarrow B$$                                $$+150$$$$3B\rightarrow 2C+D$$                      $$-125$$$$E+A\rightarrow D$$                          $$+350$$For $$B+D\rightarrow E+2C$$,            $$\triangle H$$ will be :
• $$325 kJ/ mol$$
• $$525 kJ/ mol$$
• $$-175 kJ/mol$$
• $$-325 kJ/mol$$
 An equilibrium reaction $$X+Y \rightleftharpoons W+Z, \triangle H=+ve$$ is spontaneous in the forward direction. Then corresponding sign of $$\triangle G$$ and $$\triangle S$$ should be respectively:
• +ve, -ve
• -ve , +ve
• +ve , +ve
• -ve , -ve
 Rank the following substances in order of decreasing heat of combusion (maximum $$\to$$ minimum).
• $$1 > 2 > 4 > 3$$
• $$3 > 4 > 2 > 1$$
• $$2 > 4 > 1 > 3$$
• $$1 > 3 > 2 > 4$$
 In an insulated container 1 mole of a liquid. molar volume 100 ml at 1 bar. Liquid is steeply taken to 100 bar, when volume of liquid decreases by 1 ml. Find $$\Delta H$$ for the process.
• 7900 bar mL
• 8900 bar mL
• 9900 bar mL
• 10900 bar mL
 the above reaction was carried out at 300 K in a bomb calorimeter. The heat released was 743 kJ/mol. The value of $$\triangle H_{300K}$$ for this reaction would be:
• -740.5 kJ/mol
• -741.75 kJ/mol
• -743.0 kJ/mol
• -744.25 kJ/mol
 For the reaction$$A\rightleftharpoons B+C$$ At the equilibrium, the concentration of $$A$$ is $$1\times { 10 }^{ -3 }M$$  is $$B$$ is $$0.15M$$ and $$C$$ is $$0.05M$$. The $$\triangle { G }^{ o }$$ for the reaction at $${ 27 }^{ o }C$$  will be
• $$-5kJ/ mol$$
• $$-17.36kJ/ mol$$
• $$-11.2kJ/ mol$$
• $$10.1kJ/mol$$
 Given  the following data:Substance    $$\Delta H$$(KJ/mol)     $${S^ \circ }$$(J/mol K)     $$\Delta G\,\,\,$$(KJ/mol) FeO(s)            -266.3               57.49             -245.12  C(Graphite)      0                     5.74                    0Fe(s)                 0                     27.28                  0CO(g)                -110.5              197.6                -137.15Determine at what temperature the following reaction is spontaneous ?$${\text{FeO}}\left( {\text{s}} \right){\text{ + C}}\left( {{\text{Graphite}}} \right) \to {\text{Fe}}\left( {\text{s}} \right){\text{ + CO}}\left( {\text{g}} \right)$$
• 289 K
• 668 K
• 966 K
• $${{\text{G}}^{\text{o}}}$$ is $${\text{ + ve}}$$. hence the reaction will never be spontaneous
 For the process,$${\text{C}}{{\text{O}}_{\text{2}}}\left( s \right) \to \,{\text{C}}{{\text{O}}_{\text{2}}}\left( g \right)$$
• Both $${{\Delta H}}\,\,\,\,$$ and $${{\Delta S}}$$ are negative
• $${{\Delta H}}\,\,\,\,$$ is negative and $${{\Delta S}}$$ is positive
• $${{\Delta H}}\,\,\,\,$$ is +Ve and $${{\Delta S}}$$ is negative
• Both $${{\Delta H}}\,\,\,\,$$ and $${{\Delta S}}$$ are positive
 Spontaneity may be observed in following conditions
• $$\triangle H$$ = -ve, $$\triangle S$$ = +ve
• $$\triangle H$$ = +ve, $$\triangle S$$ = +ve
• $$\triangle H$$ = -ve, $$\triangle S$$ = -ve
• All of these
 Using the data provided, calculate the multiple bond energy (kJ / mol) of a $$C=C$$ bond in $$C_{2}H_{2}$$.  (Take the bond energy of a C-H bond as 350 kJ / mol)$$2C(s) + H_{2}(g) \rightarrow C_{2}H_{2}(g)$$ $$\Delta H = 225 kJ / mol$$ $$2C(s)\rightarrow 2C(g);\Delta H= 1410kJ mol^{-1}$$$$H_2(g)\rightarrow 2H(g);\Delta H= 330kJ mol^{-1}$$
• 1165
• 837
• 865
• 815
 In a reaction, the change in entropy is given as 2.4 cal/K and the change in Gibbs free energy is given as 3.4 kcal, calculate the change in heat at the temperature of 20-degree centigrade?
• 3.4 kcal
• 3.4 cal
• 3.4 kJ
• 3.4 J
 For the reaction between $$CO_2$$ and graphite$$CO_2 (g) + C(s) \rightarrow 2CO(g)$$$$\Delta H = 170.0 KJ and \Delta s = 170 JK^{-1}$$. The reaction is spontaneous at
• 298 K
• 500 K
• 900 K
• none of the above
 An endothermic reaction is spontaneous if
• $$\Delta H> T\Delta S$$
• $$\Delta H< T\Delta S$$
• $$\Delta H= T\Delta S$$
• $$T\Delta S=0$$
 For the reaction,$$A\rightarrow B,\Delta H=+ve,\Delta S=-ve$$ This reaction is
• non-spontaneous at all temperature
• non-spontaneous at low temperature
• non-spontaneous at high temperature
• spontaneous at high temperature
 For the reaction $$X_2Y_4(l)\rightarrow 2 XY_2(g)$$ at 300 K the values of $$\Delta U$$ and $$\Delta S$$ are $$2 kcal$$ and $$20 cal K^{-1}$$ respectively. The value of $$\Delta G$$ for the reaction is:
• -3400 cal
• 3400 cal
• 2000 cal
• -2800 cal
 The reaction $$2A(g)\rightarrow A_{2}(g)$$, will be spontaneous
• At high temperature
• At low temperature
• At all temperature
• Never at any temperature
 The correct thermodynamic conditions for the spontaneous reaction at all temperature is:
• $$\Delta H < 0$$ and $$\Delta S = 0$$
• $$\Delta H > 0$$ and $$\Delta S < 0$$
• $$\Delta H < 0$$ and $$\Delta S > 0$$
• $$\Delta H < 0$$ and $$\Delta S < 0$$
 Consider the following processes:$$\frac { 1 }{ 2 } A\longrightarrow B:\quad \quad \quad \quad \quad \triangle H=150$$$$3B\longrightarrow 2C+D:\quad \quad \quad \quad \quad \triangle H=-125$$$$E+A\longrightarrow 2D\quad \quad \quad \quad \quad \quad \quad \triangle =350$$For B+D $$\rightarrow$$ E+2C,$$\triangle$$H will be:
• 325 kJ/mol
• 525 kJ/mol
• -175 kJ/mol
• -325 kJ/mol
 The difference between heat of reaction at pressure and constant volume for the reaction, $${ CH }_{ 2 }={ CH }_{ 2 }(g)+{ 3O }_{ 2 }(g)\rightarrow { 2CO }_{ 2 }(g)+{ 2H }_{ 2 }O(l)$$ at 300 K is?
• 5.87 kJ
• -4.99 kJ
• 6.89 kJ
• -7.25 kJ
 Given that $$Zn+1/2O_2\rightarrow ZnO+35.25kJ. HgO\rightarrow Hg+1/2O_2+9.11kJ.$$ The heat of the reaction $$Zn+HgO\rightarrow ZnO+Hg$$ is
• -26.14kJ
• 44.39kJ
• -44.39kJ
• 26.14kJ
 What is the free energy change $$\triangle G$$, when $$1.0$$ mole of water at $$100^{o}C$$ and $$1$$ atm pressure is converted steam at $$100^{o}C$$ and $$1$$  atm pressure:-
• +540 cal
• -9800 cal
• +9800 cal
• 0 cal
 500 J of heat was supplied to a system at constant volume.It resulted in the increase of temperature of the system from $$20^oC$$ to $$25^oC$$ .What is the change in internal energy of the system?
• $$+8.43\ J$$
• $$+43\ J$$
• $$+458.43\ J$$
• $$+580.43\ J$$
 The P - V diagram of a system undergoing a thermodynamic process is shown in figure. Work done by the system in going from $$A \rightarrow B \rightarrow C$$ is 30 J and 40 J heat is given to the system. The change in internal energy of the gas if the gas is directly taken from A to C  is
• 10 J
• 70 J
• 84 J
• 134 J
 $$2A{ l }_{ 2 }(s)\longrightarrow 4Al(s)+3{ O }_{ 2 }(g),\triangle G=+138$$ kcal considering the contributing of entropy to the spontaneity of this reaction, the reaction is________And entropy of the system_______.
• Spontaneous increase
• Spontaneous decrease
• non-Spontaneous, increase
• non-Spontaneous decrease
 For reaction $$A \rightarrow B$$, $$\Delta H$$ and $$\Delta S$$ are positive. the most favourable condition of spontaneous process.
• low temperature
• high temperature
• high concentration
• very low temperature
 The Gibb's energy for the decomposition of $$Al_{2}O_{3}$$ at $$500^oC$$ is as follows:$$2/3A{ l }_{ 2 }{ O }_{ 3 }\longrightarrow 4/3Al+{ O }_{ 2 }{ \triangle }_{ r }G=+966\quad kJ\quad { mol }^{ -1 }$$The potential difference needed for electrolytic reduction of  $$Al_{2}O_{3}$$ at $$500^oC$$ is at least
• 5.0 V
• 4.5 V
• 3.0 V
• 2.5 V
 Dextrorotatory  $$\alpha$$  -pinene has a specific rotation  $$[ \alpha ] _ { D } ^ { 20 } = + 51.3 ^ { \circ } .$$  A sample of  $$\alpha -pinene$$  containing both the enantiomers was found to have a specific rotation value  $$[ \alpha ] _ { D } ^ { 20 } = + 30.8 ^ { \circ } .$$  The percentages of the  $$( + )$$  and  $$( - )$$  enantiomers present in the sample are, respectively.
• $$70 \%$$ and $$30 \%$$
• $$80 \%$$ and $$20 \%$$
• $$20 \%$$ and $$80 \%$$
• $$60 \%$$ and $$40 \%$$
 $$\begin{array}{l}N{H_3}\left( g \right) + 3C{l_2} \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} NC{l_4}\left( g \right) + 3HCl: - \Delta {H_1}\\{N_2}\left( g \right) + 3{H_2}\left( g \right) \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} 2N{H_3}\left( g \right):\Delta {H_2}\\{H_2}\left( g \right) + C{l_2}\left( g \right) \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} 2HCl\left( g \right):\Delta {H_3}\end{array}$$The heat of formation of $$NC{l_4}$$ in the terms of $$\Delta {H_1},\Delta {H_2},\Delta {H_3}$$ is:
• $$\Delta {H_1} = - \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$
• $$\Delta {H_1} = \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$
• $$\Delta {H_1} = \Delta {H_1} - \dfrac{{\Delta {H_2}}}{2} + \dfrac{3}{2}\Delta {H_3}$$
• none of these
 An ideal gas expands according to the law $$P^{2}V$$= constant. The internal energy of the gas
• Increases continuously
• Decreases continuously
• Remain constant
• First increases and then decreases
 In which of the following ionic compounds, $$\Delta H_f$$ is negative only due to lattice energy: (i) $$NaF$$       (ii) $$MgO$$        (iii)$$Li_2N$$      (iv)$$Na_2S$$
• Only (iv)
• Only (iii) and (iv)
• Only (ii), (iii), (iv)
• All of these
 When a bottle of perfume is opened, odorous molecules mix with air and slowly diffuse throughout the entire room. The incorrect fact about the process is:
• $$\triangle G = -Ve$$
• $$\triangle H \simeq 0$$
• $$\triangle S = -Ve$$
• $$\triangle S = +ve$$