CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 15 - MCQExams.com

Assuming that water vapour is an ideal gas, the internal energy change  $$(\Delta  U) $$ when  $$1 mol$$  of water is vapourised at  $$1 bar$$ pressure and   $$100 ^ { \circ } C .$$ (Given: Molar enthalpy of vapourisation of water at  $$1 bar$$  and  $$373 K = 41 kJ mol ^ { -1 }$$  and  $$R = 8.3 \mathrm { Jmol } ^ { - 1 } \mathrm { K } ^ { - 1 } \text { will be } )$$
  • $$4.100 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$
  • $$3.7904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$
  • $$37.904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$
  • $$41.00 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$
Which one of the following is correct?
  • $$-\Delta G = \Delta H - T \Delta S  $$
  • $$-\Delta H = \Delta G - T \Delta S  $$
  • $$-\Delta S = \dfrac{1}{T}[\Delta G - \Delta H] $$
  • $$-\Delta S = \dfrac{1}{T}[\Delta H - \Delta G] $$
The internal energy of a gas in an adiabatic process is given by $$U=a+bPV$$  find y:-
  • $$\dfrac { a+1 }{ a } $$
  • $$\dfrac { b+1 }{ b } $$
  • $$\dfrac { b+1 }{ a } $$
  • $$\dfrac { a }{ b+1 } $$
The $$\Delta H$$ and $$\Delta S$$ for a reaction at one atmospheric pressure are $$+30.558\ KJ$$ and $$+0.066\ KJ$$ respectively. The temperature at which the free energy changes will be zero and below this temperature, the nature of the reaction would be
  • $$483\ K,spontaneous$$
  • $$443\ K,non-spontaneous$$
  • $$463\ K,spontaneous$$
  • $$463\ K,non-spontaneous$$
Consider the following reaction .
$${C_6}{H_6}\left( \ell  \right) + {{15} \over 2}{O_2}\left( g \right) \to 6C{O_2}\left( g \right) + 3{H_2}O\left( g \right)$$
Signs of $$\Delta H,$$ $$\Delta S$$ $$\Delta G$$ for the above reaction will be;
  • $$ + ,\,\, - ,\,\, + $$
  • $$ - ,\,\, + ,\,\, + $$
  • $$ - ,\,\, + ,\,\, - $$
  • $$ + ,\,\, + ,\,\, - $$
The standard reduction potentials for $$ Zn^{2+} /Zn, Ni^{2+} / Ni $$ and $$ Fe^{2+}  $$ are -0.76, -0.23 and -0.44V respectively. The reduction $$ X +Y^{2+} \rightarrow X^{2+} +Y $$ will be spontaneous when :
  • X = Ni, Y = Zn
  • X=Fe, Y = Zn
  • X = Zn, Y = Ni
  • X = Ni, Y= Fe
The internal energy of gases $$He, O_{2}$$ and $$NH_{3}$$ are plotted against the absolute temperature. The respective graphs $$1, 2$$ and $$3$$ are of?
1312512_ed7a6978d6e84908a440115eefae4443.png
  • $$He, O_{2}$$ and $$NH_{3}$$
  • $$NH_{3}, H_{2}$$ and $$O_{2}$$
  • $$NH_{3}, O_{2}$$ and $$He$$
  • $$O_{2}, He$$ and $$NH_{3}$$
For the reaction at 298K $$CaCO_{3}(s)\rightarrow CaO(s)+CO_{2}(g), \Delta H^{o}=178.3kJ,\Delta S^{o}=160Jk^{-1}$$
Select correct statement$$(s)$$:
  • The reaction is sponteneously at this temperature $$(298 K)$$
  • If temperature is decrease forward reaction is fevoured
  • The reaction is spontaneously in forward direction onlt at temperature above $$1000K$$
  • The reaction is spontaneously in forward direction onlt at temperature above $$1.114K$$
Consider the following reaction
$${{\text{C}}_{\text{6}}}{{\text{H}}_{\text{6}}}\left( \ell  \right){\text{ + }}\frac{{{\text{15}}}}{{\text{2}}}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right) \to {\text{6C}}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right){\text{ + 3}}{{\text{H}}_{\text{2}}}{\text{O}}(g)$$
Signs of $$\Delta {\text{H,}}\,\,\Delta {\text{S}}\,{\text{and}}\,\Delta {\text{G}}$$ for the above reaction will be:
  • + , - , +
  • - , + , -
  • - , + , +
  • + , + , -
$$ \triangle G$$ of the conversion of 2 mol of $$ C_6H_6(I)  at 80^oC $$ (normal boiling point) to vapour at the same temperature and a pressure of 0.2 atm is: 
  • -9.44 Kcl/mol
  • -2.27 Kcal/mol
  • -1.135 Kcal/mol
  • zero
Heat of $$30 kcal$$ is supplied to a system and $$4200 J$$ of external work is done on the system so that  its volume decreases at constant pressure. What is the change in its internal energy. $$=(J=4200J/kcal)$$
  • $$1.302\times 10^5J$$
  • $$2.302\times 10^5J$$
  • $$3.302\times 10^5J$$
  • $$4.302\times 10^5J$$
A diatomic gas is heated at constant at constant pressure. What fraction of the heat energy is used to increase the internal energy ?
  • $$\dfrac 3 5$$
  • $$\dfrac 3 7$$
  • $$\dfrac 5 7$$
  • $$\dfrac 5 9$$
The enthaply change on freezing of $$1\ mol$$ of water at $$10^ {o}C$$ to ice at $$-10^ {o}C$$ is:
  • $$6.56\ kJ\ mol^ {-1}$$
  • $$5.81\ kJ\ mol^ {-1}$$
  • $$6.00\ kJ\ mol^ {-1}$$
  • $$5.64\ kJ\ mol^ {-1}$$
Given that:
(i) $$C$$ (graphite)$$+O_2(g)\rightarrow CO_2(g)$$; $$\quad \Delta _rH^o=x\ kJ mol^{-1}$$.
(ii) $$C$$ (graphite)$$+\dfrac{1}{2}O_2(g)\rightarrow CO(g)$$; $$\quad \Delta _rH^o=y\ kJ mol^{-1}$$
(iii) $$CO(g)+\dfrac{1}{2}O_2(g)\rightarrow CO_2(g)$$; $$\quad \Delta _rH^o=z\ kJ mol^{-1}$$

Based on the given thermochemical equations, find out which one of the following algebraic relationships is correct?
  • $$z=x+y$$
  • $$x=y-z$$
  • $$x=y+z$$
  • $$y=2z-x$$
The sole criterion for the spontaneity of a process is 
  • tendency to acquire minimum energy
  • Tendency to acquire maximum randomness
  • Tendency to acquire minimum energy and maximum randomness
  • tendency to acquire maximum stability
The internal energy of an ideal gas increases when it 
  • Expands
  • Is compressed
  • Is first expanded and then compressed
  • None of these
A reaction is spontaneous at low temperature but non-spontaneous at high temperature. Which of the following is true for the reaction?
  • $$\triangle H > 0,\triangle S > 0$$
  • $$\triangle H < 0,\triangle S > 0$$
  • $$\triangle H > 0,\triangle S=0$$
  • $$\triangle H < 0,\triangle S < 0$$
  • $$\triangle H = 0,\triangle S < 0$$
At $$ 27^oC $$ the reaction,
$$ C_6H_{6(1)} + \dfrac{15}{2} O_{2(g)} \rightarrow 6CO_{2(g)} +3H_2O_{(I)} $$
proceeds spontaneously because the magnitude of 
  • $$ \Delta H=T\Delta S $$
  • $$ \Delta H\ >\ T\Delta S $$
  • $$ \Delta H\ <\ T\Delta S $$
  • $$ \Delta H\ >\ 0\ and\ T\Delta S\ <\ 0 $$
In a thermodynamic process, pressure of a fixed mass of a gas is changed in such a manner that the gas molecules gives out 20 J of heat and 10 J of work is done on the gas. If the initial internal energy of the gas was 40 J, then the final internal energy will be 
  • $$30 J$$
  • $$20 J$$
  • $$60 J$$
  • $$40 J$$
A process has $$\Delta H = 200 \,J \,mol^{-1}$$ and $$\Delta S = 40 \,JK \,mol^{-1}$$. Out of the values given above which the process will be sponteneous:
  • $$5 \,K$$
  • $$4 \,K$$
  • $$20 \,K$$
  • $$12 \,K$$
A thermodynamical process is shown in the figure. The pressure and volumes corresponding to some points in the figure are$${ P }_{ A } = 3 \times {10}^{4} Pa$$ $${ V }_{A} = 2 \times {10}^{-3} { m }^{3} $$$${ P }_{ B } = 8 \times {10}^{4} Pa$$ $${ V }_{D} = 5 \times {10}^{-3} { m }^{3} $$In the process $$AB$$, $$600 J$$ of heat is added to the system and in process $$BC 200 J$$ of heat is added to the system. The change in internal energy of the system in process $$AC$$ would be
1376217_aff3af536e7a4b138f58198f11226872.PNG
  • $$560 J$$
  • $$800 J$$
  • $$600 J$$
  • $$640 J$$
Ethyl chloride $$(C_{2}H_{5}Cl)$$ is prepared by:-

$$C_{2}H_{4(g)}+HCl_{(g)}\rightarrow C_{2}H_{5}Cl_{(g)};\ \ \Delta H=-72.3 kJ$$ if 98 g of $$C_{2}H_{4}$$ and 109.5 g $$HCl$$ are used at 300 K, then find $$\Delta E$$.
  • -64.8 kJ
  • -190 kJ
  • 209.4 kJ
  • -209.4 kJ
A gas is compressed at a constant pressure of 50 $$N/m^{ 2 }$$ from a volume of $$10m^{ 3 }$$ to a volume of $$4m^{ 3 }$$. Energy of 100 J is then added to the gas by heating. Its internal energy is
  • increased by 400 J
  • increased by 200 J
  • increased by 100 J
  • decreased by 400 J
Which relationship is incorrect? (for reversible isothermal process)
  • $$\Delta H=\Delta U+\Delta n_{g}$$ RT(for reaction)
  • $$\Delta G= T \Delta S$$
  • $$\Delta G^{\circ}=-2.303$$ RT log K
  • W= +2.303 nRT log $$\frac{V_{1}}{V_{2}}$$
The amount of heat energy required to raise the temperature $${\text{1}}\,{\text{g}}$$ of Helium at $${\text{NTP}}$$, from $${\text{T,K}}$$ to $${{\text{T}}_2}{\text{K}}$$ is  
  • $$\frac{3}{2}{N_a}{k_B}\left( {{T_2} - {T_1}} \right)$$
  • $$\frac{3}{4}{N_a}{k_B}\left( {{T_2} - {T_1}} \right)$$
  • $$\frac{{\text{3}}}{{\text{4}}}{{\text{N}}_{\text{a}}}{{\text{k}}_{\text{B}}}\left( {\frac{{{{\text{T}}_{\text{2}}}}}{{{{\text{T}}_{\text{1}}}}}} \right)$$
  • $$\frac{{\text{3}}}{8}{{\text{N}}_{\text{a}}}{{\text{k}}_{\text{B}}}\left( {{T_2} - {T_1}} \right)$$
The amount of heat required to raise the temperature of 1 mole diatomic gas by $$1^0C$$ a constant pressure is 60 cal. The amount of heat which goes as internal energy of the gas is nearly
  • 60 cal
  • 30 cal
  • 42.6 cal
  • 49.8 cal
Energy required to dissociate, 16 g oxygen gas into free atom is x kJ. The heat of atomisation of oxygen is :-
  • x/2
  • 2x
  • x
  • 16
A process has $$\Delta H=200 J mol^{-1}$$ and $$\Delta S=40 JK^{-1} mol^{-1}$$. Out of the values given below, choose the minimum temperature above which the process will be spontaneous?
  • 4 K
  • 20 K
  • 5 K
  • 12 k
For a spontaneous process, if entropy and volume are constant, the internal energy system must
  • Increase
  • Decrease
  • Remain constant
  • Be zero
A process is said to be spontaneous if
  • $$\triangle G = -ve$$
  • $$\triangle G^{\circ} = -ve$$
  • $$\triangle H = -ve$$
  • $$\triangle H^{\circ} = -ve$$
A reaction has $$\triangle H = -33\ kJ$$ and $$\triangle S = +58\ J/K$$. This reaction would be:
  • spontaneous below a certain temperature
  • non-spontaneous at all temperature
  • spontaneous above a certain temperature
  • spontaneous at all temperature
A body cools from $$71^0C$$ to $$69^0C$$ in $$4$$ minutes. If the surrounding temperature is constant at $$20^0C$$. Time taken by the body to cool from $$61^0C$$ to $$59^0C$$ is
  • $$5$$ minutes
  • $$4$$ minutes
  • $$6$$ minutes
  • $$3$$ minutes
The correct thermodynamic conditions for the spontaneous reaction at all temperatures is ______________________.
  • $$\Delta H < 0 \quad and\quad \Delta S < 0$$
  • $$\Delta H < 0 \quad and\quad \Delta S = 0$$
  • $$\Delta H > 0 \quad and\quad \Delta S < 0$$
  • $$\Delta H < 0 \quad and\quad \Delta S > 0$$
An ideal monoatomic gas is taken through a process in which $$d Q = 2 d U$$ . The molar heat capacity of the gas for the process is
  • $$R$$
  • $$2R$$
  • $$3R$$
  • $$4R$$
Which of the following integrals depends only on the initial and final states of a thermodynamic system (i.e., independent of the path of transformation)? 
  • $$
    \int P d V
    $$
  • $$
    \int d Q
    $$
  • $$
    \int T^2 d S
    $$
  • none of these
The P-V diagrams of two difference masses $$m_1$$ and $$m_2$$ for an ideal gas at constant temperature $$T$$is given in the figure below.
1388979_0c713dc00b0548e69af07fcc0b05b938.PNG
  • $$m_1 = m_2$$
  • $$m_1 < m_2$$
  • $$m_1 > m_2$$
  • Data insufficient
Correct desending order of deprotonation in the following compound:
1439064_a5763cce475b4755892d1ccc676a5b0a.png
  • e > d > c > b > a
  • e > d > c > a > b
  • e > c > b > d > a
  • e > c > b > a > d
Using the Gibbs energy change ,$${ \Delta G }^{ \circ  }=+63.3 kJ,$$ for the following reaction,$${ Ag }_{ 2 }{ CO }_{ 3 }\rightleftharpoons 2Ag\left( sq \right) +{ CO }^{ 2- }_{ 3 }\left( aq \right) $$ the $${ K }_{ sp }of{ Ag }_{ 2 }{ CO }_{ 3 }\left( s \right) $$ in water at $${ 25 }^{ \circ  }C$$ is:-

$$\left( R={ 8.314\quad j=J\quad k }^{ -1 }{ mol }^{ -1 } \right) $$
  • $${ 3.2\times 10 }^{ -26 }$$
  • $${ 8.0\times 10 }^{ -12 }$$
  • $${ 2.9\times 10 }^{ -3 }$$
  • $${ 7.9\times 10 }^{ -2 }$$
 A gas mixture consists of $$2$$ moles of O, and $$4$$ moles of Ar at a temperature T. Neglecting all vibrational moles, the total internal energy of the system is 
  • $$4RT $$
  • $$15RT $$
  • $$9RT$$
  • $$11RT$$
Hess's law states that:
  • The standard enthalpy of an overall reaction is the sum of the enthalpy changes in individual reactions.
  • Enthalpy of formation of a compound is same as the enthalpy of decomposition of the compound into constituent elements, but with opposite sign.
  • At constant temperature, the pressure of a gas is inversely proportional to its volume
  • The mass of a gas dissolve per liter of a solvent is proportional to the pressure of the gas in equilibrium with the solution.
Which of the following are spontaneous?
  • dissolution of sugar
  • separation of Ar and Kr from their mixture
  • spreading of fragrance when a bottle of perfume is opened
  • Flow of heat from cold object to hot object
  • heat transfer from ice to room at $$ 25^0 C $$
One mole of an ideal monatomic gas undergoes a process described by the equation $$PV^{3}$$ = constant. The heat capacity of the gas during this process is:
  • $$R$$
  • $$\dfrac{3}{2R}$$
  • $$\dfrac{5}{2R}$$
  • $${2R}$$
Assertion : A reaction which is spontaneous and accompanied by decrease of randomness must be exothermic.
Reason : All exothermic reactions are accompanied by decrease of randomness.
  • both assertion and reason are true and the reason is the correct explanation of assertion.
  • both assertion and reason are true but the reason is not the correct explanation of assertion.
  • assertion is true but reason is false.
  • both assertion and reason are false
A reaction A(g) +B(g) $$\rightarrow $$ C(g) +D(g). $$\Delta H$$= (-) ve is found to have positive entropy change. the reaction will be: 
  • Spontaneous at high temperature
  • Spontaneous only at low temperature
  • Not spontaneous at any temperature
  • Spontaneous at any temperature
In which case, process will be spontaneous at all temperatures?
  • $$\Delta H<0,$$ $$\Delta S>0$$
  • $$\Delta H>0,$$ $$\Delta S>0$$
  • $$\Delta H<0,$$ $$\Delta S<0$$
  • $$\Delta H>0,$$ $$\Delta S<0$$
Consider the following reaction occurring in an automobile:
$$2C_8H_{18(g)} + 25 O_{2(g)} \rightarrow 16 CO_{2(g)} + 18H_2O_{(g)}$$, the sign of $$\Delta H, \ \Delta S$$ and $$\Delta G$$ would be:
  • $$+, -, +$$
  • $$-, +, -$$
  • $$-, +, +$$
  • $$+, +, -$$
$$100g$$ of water is heated from $${30}^{o}C$$ to $${50}^{o}C$$. Ignoring the slight expansion of water, the change in its internal energy is (Specific heat of water is $$4200J$$ $${kg}^{-1}$$ $${K}^{-1}$$)
  • $$4.2kJ$$
  • $$84kJ$$
  • $$2.1kJ$$
  • $$8.4kJ$$
The heat energy of $$743J$$ is needed to raise the temperature of $$5$$ moles of an ideal gas by $$2K$$ at constant pressure. How much heat energy is needed to raise the temperature of the same mass of the gas by $$2K$$ at constant volume?
  • $$826J$$
  • $$743J$$
  • $$660J$$
  • $$600J$$

A student mixed 25.0cm3 of 4.00 moldm–3 hydrochloric acid with an equal volume of 4.00moldm–3 sodium hydroxide.?

The initial temperature of both solutions was 15.0°C. The
maximum temperature recorded was 30.0°C.
Using these results, what is the enthalpy change of neutralisation of hydrochloric acid?
  • $$-62.7kJ$$ $${mol}^{-1}$$
  • $$-31.4kJ$$ $${mol}^{-1}$$
  • $$-15.7kJ$$ $${mol}^{-1}$$
  • $$-3.14kJ$$ $${mol}^{-1}$$
Any process will be spontaneous at constant pressure and temperature when:
  • $$\Delta { S }_{ system }=+ve$$
  • $$\Delta { S }_{ univ. }=+ve$$
  • $$\Delta { G }_{ sys }=-ve$$
  • $$\Delta { G }_{ univ. }=+ve$$
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 11 Medical Chemistry Quiz Questions and Answers