CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 7 - MCQExams.com

A barometer made of very narrow tube is placed at normal temperature and pressure. The coefficient of volume expansion of mercury is $$0.00018$$ per $$^oC$$ and that of the tube is negligible. The temperature of mercury in the barometer is now raised by $$1^o$$C, but the temperature of the atmosphere does not change. Then the mercury height in the tube remains unchanged.
1010522_545cb3c8d9db4c1c8b7a9502100cdd9e.png
  • True
  • False
The specific heat of copper is $$0.385$$ J/(g. $$^oC$$). If $$34.2$$ g of copper, initially at $$25^o$$C, absorbs $$4.689$$ kJ, what will be the final temperature of the copper?
  • $$25.4^o$$C
  • $$27.8^o$$C
  • $$356^o$$C
  • $$381^o$$C
If Q increases then:
  • $$\Delta G$$ increases and the reaction becomes more spontaneous.
  • $$\Delta G$$ increases and the reaction becomes less spontaneous.
  • $$\Delta G$$ decreases and the reaction becomes more spontaneous.
  • $$\Delta G$$ decreases and the reaction becomes less spontaneous.
Which heat is produced throughout the conducting wire?
  • Petlier heat
  • Thomson effect heat
  • Joule heat
  • none of these
Magnitude of Seebeck emf between the junctions does not depend on
  • thermocouple
  • temperature of cold junction
  • temperature of hot function
  • neutral temperature
The value of $$\triangle $$H and $$\triangle $$S for the reaction, $${ C }_{ \left( graphite \right)  }+{ CO }_{ 2\left( g \right)  }\rightarrow 2{ CO }_{ (g) }$$ are 170kJ  and $${ 170JK }^{ -1 }$$, respectively. This reaction will be spontaneous  at:
  • 510K
  • 710K
  • 910K
  • 1119K
For an exothermic reaction to be sponteneous:
  • temperature must be high
  • temperature must be zero
  • temperature may have any magnitude
  • temperature and $$\Delta H < T \Delta S$$.
For a reversible spontaneous change $$\triangle s$$ is:
  • $$\dfrac { \triangle E }{ T } $$
  • $$\dfrac { P\triangle V }{ T } $$
  • $$\dfrac { q }{ T } $$
  • $$RTlogK$$
For a process to be spontaneous at constant $$T$$ and $$P$$:
  • $$(\Delta G)_{system}$$ must be negative
  • $$(\Delta G)_{system}$$ must be positive
  • $$(\Delta S)_{system}$$ must be positive
  • $$(\Delta S)_{system}$$ must be negative
Which of the following must be spontaneous at all temperatures?
  • $$\Delta H_{sys}=-ve; \Delta S_{sys}=-ve$$
  • $$\Delta H_{sys}=-ve; \Delta S_{sys}=+ve$$
  • $$\Delta H_{sys}=+ve; \Delta S_{sys}=+ve$$
  • $$\Delta H_{sys}=+ve:; \Delta S_{sys}=-ve$$

Specific heats of monoatomic and diatomic gases are same and
satisfy the relation which is
  • $${C_p}\left( {mono} \right) = {C_p}\left( {dia} \right)$$
  • $${C_p}\left( {mono} \right) = {C_\upsilon }\left( {dia} \right)$$
  • $${C_\upsilon }\left( {mono} \right) = {C_\upsilon }\left( {dia} \right)$$
  • $${C_\upsilon }\left( {mono} \right) = {C_p}\left( {dia} \right)$$
$$Pt$$ | $$Cl_2$$ ($$P_1$$ atm) | $$HCl$$ ($$0.1$$M) | $$Cl_2$$ ($$P_2$$ atm) | $$Pt$$, cell reaction will be spontaneous if:
  • $$P_1 = P_2$$
  • $$P_1 > P_2$$
  • $$P_2 > P_1$$
  • $$P_1 = P_2 =1$$ atm
In the series $$Sc(Z=21)$$ to $$Zn(Z=30)$$, the enthalpy of atomisation of which element is least?
  • Sc
  • Mn
  • Cu
  • Zn
The value closest to the thermal velocity of a Helium atom at room temperature (300 K) in $$ms^{-1}$$ is : [$$k_B = 1.4 \times 10^{-23} \ J/K ; \ m_{He} = 7\times 10^{-27} \ kg$$ ]
  • $$1.3 \times 10^4$$
  • $$1.3 \times 10^3$$
  • $$1.3 \times 10^5$$
  • $$1.3 \times 10^2$$
For the reaction of one mole zinc dust with one mole sulphuric acid in a bomb calorimeter, $$\triangle U$$ and w correspond to?
  • $$\triangle U<0,w=0$$
  • $$\triangle U<0,w<0$$
  • $$\triangle U>0,w=0$$
  • $$\triangle U>0,w>0$$
The specific heat of a metal is $$0.26$$. The chloride of the metal (always monomer) has its molecular mass $$95$$. The volume of hydrogen gas that $$1.2g$$ of the metal will evolve at $${0}^{o}C$$ and $$1$$ atm, if it is allowed to react with excess of an acid, is ?
  • $$2.24L$$
  • $$1.12L$$
  • $$0.56L$$
  • $$5.61L$$
For a gas having molar mass M, specific heat at constant pressure can be given as:
  • $$\dfrac { \gamma R }{ M\left( \gamma -1 \right) } $$
  • $$\dfrac { \gamma }{ RM } $$
  • $$\dfrac { M }{ R\left( \gamma -1 \right) } $$
  • $$\dfrac { \gamma RM }{ \gamma +1 } $$
For $$ { Zn }^{ 2+ }/Zn $$ ,
$$ { E }^{ \circ  }=-0.76\quad V $$,
for $$ { Ag }^{ + }/Ag\quad { E }^{ \circ  }=\quad 0.799\quad V $$.
The correct statement is:
  • Zn undergoes reduction and Ag is oxidized
  • in the reaction Zn getting reduced, Ag getting oxidized is spontaneous
  • Zn undergoes oxidation $$Ag^+$$ gets reduced
  • no suitable answer
Suppose that a reaction has $$\Delta H=40\ kJ$$ and $$\Delta S=50\ kJ/ K$$. At what temperature range will it change from spontaneous to non-spontaneous?
  • $$0.8\ K$$ to $$1\ K$$
  • $$799\ K$$ to $$800\ K$$
  • $$800\ K$$ to $$801\ K$$
  • $$799\ K$$ to $$801\ K$$
For the reaction; $${ FeCO }_{ 3(s) }\longrightarrow { Fe }O_{ (s) }+C{ O }_{ 2 }(g)$$, $$\Delta H=82.8\ kJ$$ at $${ 25 }^{ 0 }C$$. What is $$\Delta U$$ at $${ 25 }^{ 0 }C$$?
  • $$82.8 kJ$$
  • $$80.32 kJ$$
  • $$-2394.77 kJ$$
  • $$85.28 kJ$$
For a reaction to occur spontaneously:
  • $$\Delta S$$ must be negative
  • $$(-\Delta H+T \Delta S)$$ must be positive
  • $$\Delta H+T\Delta S$$ must be negative
  • $$\Delta H$$ must be negative
For a first order reaction rate constant is $$1 \times {10^{ - 5}}{\sec ^{ - 1}}$$ having $${E_a} = 1800\ kJ/mol$$ . Then the value of $$\ell nA$$ at$$T = 600\ K$$ is:-
  • $$151.7$$
  • $$349.3$$
  • $$24.7$$
  • $$11.34$$
$$\Delta S $$ for $$4Fe_(s)+3O_{2(g)}\rightarrow 2Fe_2O_{3(s)}$$ is $$550J/mol/K$$. The process is found to be spontaneous even at $$298K$$ $$[\Delta H=-1650kJ]$$
  • $$\Delta S_{total}=-2000J$$
  • $$\Delta S_{total}=+1650J$$
  • $$\Delta S_{total }=+4980J$$
  • $$\Delta S_total =-4980J$$
$$0.1 \,{m^3}$$ of water at $${80^ \circ }$$ is mixed with $$0.3 {m^3}$$ of water at $${60^ \circ }$$. The final temperature of mixture is :
  • $${80^ \circ }C$$
  • $${70^ \circ }C$$
  • $${60^ \circ }C$$
  • $${75^ \circ }C$$
The spontaneous nature of a reaction is impossible only if:
  • $$\Delta H=+{ve}, \Delta S=+{ve}$$
  • $$\Delta H=-{ve}, \Delta S=-{ve}$$
  • $$\Delta H=-{ve}, \Delta S=+{ve}$$
  • $$\Delta H=+{ve}, \Delta S=-{ve}$$
Which of the following set of condition necessarily implies a spontaneous process? 
  • Exothermic reaction with increasing disorder
  • Endothermic reaction with increasing disorder
  • Exothermic reaction with decreasing disorder
  • Endothermic reaction with decreasing disorder
Which of the natural process is spontaneous?
  • Formation of curd from milk after doing initiation
  • Convesion of $$C (graphite) \rightarrow C (diamond)$$ at $$25^0$$C and $$1$$atm
  • Formation of $$H_2$$ (g) and $$O_2$$(g) from $$H_2O$$(l)
  • Formation of $$CrO_5$$ from $$H_2O_2$$ and $$K_2Cr_2O_7$$ in basic medium
The specific heat of a metal is 0.16 cal/g approximate atomic weight would be:
  • $$40$$
  • $$16$$
  • $$32$$
  • $$64$$
Choose the correct statement.
  • All spontaneous natural processes are thermodynamically irreversible.
  • Work done is a state function.
  • Work done is zero during an adiabatic expansion.
  • For a spontaneous process it is always true that $$\Delta S_{system}>0$$.
The incorrect criterion for the spontaneity of a process is:
  • $$\Delta S_{system }<0$$
  • $$\Delta S_{system }+\Delta S_{surrounding }>0$$
  • $$\Delta S_{system }>\Delta S_{surrounding }$$
  • $$\Delta H_{system }<0$$ and $$\Delta S_{system}>0$$
Consider the following sequence of reactions 
Which of the following is always true?
1122160_d026fed088374e568fe0c25e46a34bec.png
  • $$\Delta H_1=\Delta H_2+\Delta H_3+\Delta H_4$$
  • $$\Delta H_2=\Delta H_1+\Delta H_3+\Delta H_4$$
  • $$\Delta H_3=\Delta H_1+\Delta H_2+\Delta H_4$$
  • $$\Delta H_4=\Delta H_1+\Delta H_2+\Delta H_3$$
An imaginary reaction $$X\rightarrow Y$$ takes place in three steps $$X\rightarrow A,\Delta H=-q_{1}$$; $$B\rightarrow A,\Delta H=-q_{2}$$; $$Y\rightarrow B,\Delta H=-q_{3}$$ If Hess' law is applicable, then the heat of the reaction $$ X \rightarrow Y $$ is:
  • $$ q_{1}-q_{2}+q_{3} $$
  • $$ q_{2}-q_{1}+q_{3} $$
  • $$ q_{1}-q_{2}-q_{3} $$
  • $$ q_{3}-q_{2}-q_{1} $$
Which of the following is true?
  • $$C_{sp}=C_m \times $$ molar mass
  • $$C_m=C_{sp} \times $$ molar mass
  • $$C_m-C_{sp}=$$ molar mass
  • $$C_m+C_{sp}=$$ molar mass
For a gaseous reaction involving the complete combustion of isobutane:
  • $$\triangle H = \triangle E$$
  • $$\triangle H > \triangle E$$
  • $$\triangle H < \triangle E$$
  • none of these
$$C(s) + O_2(g) \to CO_2(g); \quad \Delta H = -94kcal$$

$$2CO(g) + O_2(g) \to 2CO_2(g); \quad \Delta H = -135.2 kcal$$

The heat of formation of $$CO(g)$$ is :
  • $$-26.4\ kcal$$
  • $$41.2\ kcal$$
  • $$26.4\ kcal$$
  • $$229.4\ kcal$$
Select the  incorrect statement about the specific heats of a gaseous system?
  • specific heat at no exchange condition, $$C_{ A }=0$$
  • Specific heat at contant temperature, $$C_{ T }=\infty $$
  • Specific heat at constant pressure,$$C_{ P }=\frac { \gamma R }{ \gamma -1 } $$
  • Specific heat at constant volume, $$C_{ V }=\frac { R }{ \gamma } $$
Consider the reaction, $$2A_{(g)} + B_(g) rightleftarrow 2C_{(g)}$$ for which $$K_c = 350$$. If $$0.01$$ mole of each of the reactants and product are mixed in a $$2.0$$L flask, then the reaction quotient and the spontaneous direction of the system will be?
  • $$Q_c = 0.002$$; the equilibrium shifts to the left
  • $$Q_c = 2000$$; the equilibrium shifts to the left
  • $$Q_c = 0.002$$; the equilibrium shifts to the right
  • $$Q_c = 2000$$; the equilibrium shifts to the right
Consider the following reaction,
$$2A + B \rightarrow C + 2D$$, $$\Delta H_{1} = 10$$
$$A + 2C \rightarrow 2D + B$$, $$\Delta H_{2} = -5$$ What is $$\Delta H$$ of reaction $$A + 2B \rightarrow 3C$$?
  • $$-5$$
  • $$+5$$
  • $$+10$$
  • $$+15$$
For which one of the following system $$\Delta E < \Delta H$$?
  • $$2SO_{2(g)}+O_{2(g)} \rightarrow 2SO_{3(g)}$$
  • $$N_{2(g)}+O_{2(g)} \rightarrow 2NO_{(g)}$$
  • $$2NH_{3(g)} \rightarrow N_{2(g)}+3H_{2(g)}$$
  • $$H_{2(g)}+I_{2(g)} \rightarrow 2HI_{(g)}$$
At $$300 \,K$$, the reactions which have following values of thermodynamic occurs spontaneously
  • $$\Delta G^o = -400 \,kJ \,mol^{-1}$$
  • $$\Delta H^o = -200 \,kJ \,mol^{-1}, \Delta S^o = 4 \,kJK^{-1}mol^{-1}$$
  • $$\Delta H^o = 200 \,kJ \,mol^{-1}, \Delta S^o = 4k \,JK^{-1} mol^{-1}$$
  • all of these
The pressure at the base of a column of liquid of length / and held at an angle $$\theta $$ to the vertical is 
  • $$\rho gl$$
  • $$\rho gl \sin { \theta }$$
  • $$\rho g\cos { \theta } $$
  • $$\rho gl\cos { \theta } $$
Which of the following expression for an irreversible process:
  • $$d{S}_{Total}> \cfrac{dq}{T}$$
  • $$d{S}_{Total}= \cfrac{dq}{T}$$
  • $$d{S}_{Total}< \cfrac{dq}{T}$$
  • $$d{S}_{Total}= \cfrac{dU}{T}$$
Calculate the amount of heat necessary to raise $$213.5 g$$ of water from $${25}^{o}$$ and $${100}^{o}C$$ Molar heat capacity of water is $$18 cal$$ $${mole}^{-1}{K}^{-1}$$
  • $$16.0125 kcal$$
  • $$12.0125 kcal$$
  • $$20.222 kcal$$
  • $$26.323 kcal$$
Identify the correct statement regarding a spontaneous process.
  • For a spontaneous process in an isolated system, the change in entropy is positive
  • Endothermic processes are never spontaneous
  • Exothermic processes are always spontaneous
  • Lowering of energy in the reaction process is the only criterion for spontaneity
Heat of formation of $$H_2O$$ (g) at $$25^0C$$ is -243 KJ. $$\Delta U$$ for the reaction $$H_2 (g) + \frac{1}{2} O_2  (g) \rightarrow H_2O (g) $$ at $$25^0C$$ is:
  • 241.8 KJ
  • -241.8 KJ
  • -243 KJ
  • 243 KJ
Suppose that a reaction has $$\Delta H=-40kJ$$ and $$\Delta S=-50J/K$$. At what temperature range will it change from spontaneous to non-spontaneous ?
  • $$0.79\ K$$ to $$0.81\ K$$
  • $$799\ K$$ to $$801\ K$$
  • $$801\ K$$ to $$799\ K$$
  • $$0.81\ K$$ to $$0.79\ K$$
$$\Delta H$$ and $$\Delta S$$ are $$-283\ kJ$$ and $$-87\ J\ K^{-1}$$, respectively. It was intended to carry out this reaction at $$1000, 1500, 3000$$ and $$3500\ K$$. At which of these temperatures would this reaction be thermodynamically spontaneous?
  • $$1000, 1500$$ and $$2000\ K$$
  • $$500, 3000$$ and $$3500\ K$$
  • $$1500$$ and $$3500\ K$$
  • $$3000$$ and $$3500\ K$$
Which of the following statements is wrong?
  • Evaporation is a spontaneous process.
  • Evaporation is a surface phenomenon.
  • Vapour pressure decreases with increase of temperature.
  • The vapour pressure of a solution is always less than the vapour pressure of a pure solvent.
Which of the following is not true about a reversible reaction?
  • The reaction does not proceed to completion
  • It cannot be influenced by a catalyst
  • Number of moles of reactants and products is always equal
  • It can be attained only in a closed container
For the reaction: 
$${ C }_{ 2 }{ H }_{ 4 }(g)+3{ O }_{ 2 }(g)\rightarrow 2C{ O }_{ 2 }(g)+2{ H }_{ 2 }O(l)$$
$$\Delta E=-1415KJ$$. The $$\Delta H$$ at $$27C$$ is:
  • $$-1410 KJ$$
  • $$-1420 KJ$$
  • $$+1420 KJ$$
  • $$+1410 KJ $$
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