CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 4 - MCQExams.com

Two substances P and Q when brought together, form substance R with the evolution of heat. The properties of R are different from both P and Q. What is substance R?
  • A compound
  • An element
  • A metal
  • A mixture
Which describes a nonspontaneous reaction?
  • Positive $$\displaystyle \Delta H$$
  • Negative $$\displaystyle \Delta H$$
  • Positive $$\displaystyle \Delta G$$
  • Positive $$\displaystyle \Delta S$$
  • None of these
Which is the amount of energy that must be added to raise the temperature of 1 gram of a substance by $$\displaystyle { 1 }^{ \circ  }C$$?
  • Enthalpy change
  • Entropy change
  • Gibbs free energy change
  • Activation energy
  • Specific heat capacity
Which portion of the heating curve for water shown would there be ONLY liquid water present?
526729.PNG
  • $$A-B$$
  • $$B-C$$
  • $$C-D$$
  • $$D-E$$
The heat capacity for aluminum is $$\displaystyle 0.89{ Jg }^{ -10 }{ C }^{ -1 }$$, for iron is $$\displaystyle 0.45{ Jg }^{ -10 }{ C }^{ -1 }$$, and for zinc is $$\displaystyle 0.39{ Jg }^{ -10 }{ C }^{ -1 }$$. If 100 J of heat energy was added to a10 g sample of each of the metals, which of the following would be true?
  • $$\displaystyle Al$$ would have the largest temperature increase.
  • $$\displaystyle Fe$$ would have the largest temperature increase.
  • $$\displaystyle Zn $$ would have the largest temperature increase. 
  • $$\displaystyle Fe$$ and $$\displaystyle Zn$$ would have the same increase.
  • All three metals would have the same temperature increase.
Which of the following condition guarantee a spontaneous reaction?
  • Positive $$\displaystyle \Delta H$$, Positive $$\displaystyle \Delta S$$
  • Positive $$\displaystyle \Delta H$$, Negative $$\displaystyle \Delta S$$
  • Negative $$\displaystyle \Delta H$$, Negative $$\displaystyle \Delta S$$
  • Negative $$\displaystyle \Delta H$$, Positive $$\displaystyle \Delta S$$
  • None of the above
Identify the equation used to determine the amount of heat required to melt 10 grams of ice.
  • $$Q = mC_{sp} \triangle T$$
  • $$Q = n\triangle H$$
  • $$KE = \dfrac{1}{2} mv^2$$
  • $$PE = mgh$$
  • $$PV = nRT$$
Which of the following is technique used to measure the heat of a reaction?
  • Gibbs Free Energy
  • Entropy
  • Enthalpy
  • Calorimetry
$$I$$. The energy content of reactants in a chemical reaction must be equal to the energy content of the products.
$$II$$. Energy is conserved in chemical processes.
  • Statement $$I$$ is true, Statement $$II$$ is true and is a correct explanation of the phenomena described in $$I$$
  • Statement $$I$$ is true, Statement $$II$$ is false
  • Statement $$I$$ is false, Statement $$II$$ is true
  • Statement $$I$$ is false, Statement $$II$$ is false
State True or False:
I: Candles can be safely stored at room temperature/ even though their reaction with air is spontaneous at room temperature.
The reaction that takes place when a candle is burned involves a decrease in entropy.
  • True
  • False
How many calories are needed to heat $$100\ g$$ of water from $$278\ K$$ to $$288\ K$$?
  • $$10$$ calories
  • $$60$$ calories
  • $$100$$ calories
  • $$1000$$ calories
Statement I: A reaction with a positive enthalpy and a negative entropy will be spontaneous
BECAUSE
Statement II: The Gibbs free energy for a spontaneous reaction is negative
  • Statement $$1$$ and Statement $$2$$ are correct and Statement 2 is the correct explanation of Statement $$1$$
  • Both the Statement $$1$$ and Statement $$2$$ are correct and Statement $$2$$ is NOT the correct explanation of Statement $$1$$
  • Statement $$1$$ is correct but Statement $$2$$ is not correct
  • Statement $$1$$ is not correct but Statement $$2$$ is correct
  • Both the Statement $$1$$ and Statement $$2$$ are not correct
How much energy is needed to melt $$100g$$ of water?
$$\Delta {H}_{v}=540\ cal/g$$
$$\Delta {H}_{f}=80\ cal/g$$
$${C}_{water}=1\ cal/{g}^{o}C$$
  • $$640cal$$
  • $$8000cal$$
  • $$54,000cal$$
  • $$180cal$$
Which of the following conditions guarantee a spontaneous reaction?
  • Positive $$\triangle H$$, positive $$\triangle S$$
  • Positive $$\triangle H$$, negative $$\triangle S$$
  • Negative $$\triangle H$$, negative $$\triangle S$$
  • Negative $$\triangle H$$, positive $$\triangle S$$
  • None of the above
At what point of the heating curve are intermolecular forces at their greatest level?
526523_cb514e2206ac4d7bb0632145fd6e1e23.png
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
Given that $$\Delta G = \Delta H - T \Delta S$$, how is the spontaneity of an endothermic reaction expected to change with decreasing $$T$$?
  • Becomes less spontaneous
  • Becomes more spontaneous
  • Does not change
  • Decreases at first but then increases
  • Insufficient information to make a conclusion
Which selection correctly shows units for specific heat capacity?
  • $$Cal \cdot g\cdot ^{o}C$$
  • $$Cal \cdot g/ ^{o}C$$
  • $$J/(g \cdot ^{o}C)$$
  • $$g/J \cdot ^{o}C$$
What is the specific heat of a $$2.0\ g$$ sample of metal which requires the addition of $$8\ J$$ to be heated from $$293\ K$$ to $$303\ K$$?
  • $$0.4$$
  • $$0.02$$
  • $$0.6$$
  • $$2.5$$
Consider a spontaneous electrochemical cell between $$Cu$$ and $$Al$$. Predict what would happen if excess concentrated $$NaOH$$ were added to the cell with copper ions and a precipitate forms.
Standard Potential (V)Reduction Half-Reaction
$$2.87$$$$F_{2}(g) + 2e^{-} \rightarrow 2F^{-}(aq)$$
$$1.51$$$$MnO_{4}^{-}(aq) + 8H^{+}(aq) + 5e^{-}\rightarrow Mn^{2+}(aq) + 4H_{2}O(l)$$
$$1.36$$$$Cl_{2}(aq) + 3e^{-} \rightarrow 2Cl^{-}(aq)$$
$$1.33$$$$Cr_{2}O_{7}^{2-} (aq) + 14H^{+}(aq) + 6e^{-} \rightarrow 2Cr^{3+}(aq) + 7H_{2}O(l)$$
$$1.23$$$$O_{2}(g) + 4H^{+}(aq) + 4e^{-}\rightarrow 2H_{2}O(l)$$
$$1.06$$$$Br_{2}(l) + 2e^{-} \rightarrow 2Br^{-}(aq)$$
$$0.96$$$$NO_{3}^{-}(aq) + 4H^{+}(aq) + 3e^{-}\rightarrow NO(g) + H_{2}O(l)$$
$$0.80$$$$Ag^{+}(aq) + e^{-} \rightarrow Ag(s)$$$
$$0.77$$$$Fe^{3+} (aq) + e^{-} \rightarrow Fe^{2+}(aq)$$
$$0.68$$$$O_{2}(g) + 2H^{+}(aq) + 2e^{-}\rightarrow H_{2}O_{2}(aq)$$
$$0.59$$$$MnO_{4}^{-}(aq) + 2H_{2}O(l) + 3e^{-}\rightarrow MnO_{2}(s) + 4OH^{-}(aq)$$
$$0.54$$$$I_{2}(s) + 2e^{-}\rightarrow 2I^{-}(aq)$$
$$0.40$$$$O_{2}(g) + 2H_{2}O(l) + 4e^{-} \rightarrow 4OH^{-}(aq)$$
$$0.34$$$$Cu^{2+}(aq) + 2e^{-} \rightarrow Cu(s)$$
$$0$$$$2H^{+}(aq) + 2e^{-}\rightarrow H_{2}(g)$$
$$-0.28$$$$Ni^{2+}(aq) + 2e^{-}\rightarrow Ni(s)$$
$$-0.44$$$$Fe^{2+}(aq) + 2e^{-}\rightarrow Fe(s)$$
$$-0.76$$$$Zn^{2+}(aq) + 2e^{-}\rightarrow Zn(s)$$
$$-0.83$$$$2H_{2}O(l) + 2e^{-}\rightarrow H_{2}(g) + 2OH^{-}(aq)$$
$$1.66$$$$Al^{3+}(aq) + 3e^{-}\rightarrow Al(s)$$
$$-2.71$$$$Na^{+}(aq) + e^{-} \rightarrow Na(s)$$
$$-3.05$$$$Li^{+}(aq) + e^{-}\rightarrow Li(s)$$
  • Voltage would increase since more ions can give up electrons.
  • Voltage will decrease since there will be less $$Cu^{2+}$$ ions in solution.
  • Voltage would stay the same since $$NaOH$$ is a strong electrolyte and will exist as a spectator ion.
  • Voltage would increase and then decrease as the addition of new ions reach equilibrium.
To which portion of the heating curve for water does $$\Delta {H}_{fus}$$ apply?
526743.PNG
  • $$A-B$$
  • $$B-C$$
  • $$C-D$$
  • $$D-E$$
Based on knowledge of solid compounds and bond strengths, which of the following reactions is considered non-spontaneous due to the extremely high activation energy but once started becomes extremely spontaneous?
  • Dissolution of sodium hydroxide.
  • Creating a dilution of hydrochloric acid.
  • The burning of $$C_{20}H_{42}$$.
  • The synthesis of silver oxide.
Which portion of the heating curve for water shown above would there be both liquid and solid water present?
526732.PNG
  • $$A-B$$
  • $$B-C$$
  • $$C-D$$
  • $$D-E$$
To which portion of the heating curve for water does $$C=1.00 \ cal/{g}^{o}C$$ apply?
526744.PNG
  • $$A-B$$
  • $$B-E$$
  • $$C-D$$
  • $$A-F$$
The formation of carbon dioxide by reacting Carbon with excess Oxygen, is exothermic. What will be the sign of $$\Delta H$$?
  • $$\Delta H$$ is positive
  • $$\Delta H$$ is negative
  • $$\Delta H$$ is zero
  • None of these
How will the temperature of $$10.0\ g$$ of iron change if $$45\ J$$ is added to the metal?
Iron has a specific heat of $$0.45\ J/(g^oC)$$.
  • $$+20^{o}C$$
  • $$+10^{o}C$$
  • $$+100^{o}C$$
  • $$+1^{o}C$$
To which portion of the heating curve for water does $$\Delta {H}_{vap}$$ apply?
526737.PNG
  • $$A-B$$
  • $$B-C$$
  • $$C-D$$
  • $$D-E$$
$$C_v$$ for helium gas $$(He)$$ is $$(in J \ mol^{-1} \ K^{-1})$$
  • 2.5
  • 10.5
  • 1.5
  • 12.5
Carbon reacts with oxygen to produce carbon dioxide which is an exothermic reaction, where $$394\ kJ/mol$$ of heat is produced. What will be the value of $$\Delta H$$ when $$24$$ grams of carbon reacts?
  • $$+394\ kJ$$
  • $$-394\ kJ$$
  • $$+788\ kJ$$
  • $$-788\ kJ$$
The formation of nitric oxide from Nitrogen and Oxygen is endothermic in nature. What will be the sign of $$\Delta H$$?
  • $$\Delta H$$ is positive
  • $$\Delta H$$ is negative
  • $$\Delta H$$ is zero
  • None of these
A balanced stoichiometric chemical equation which includes a change in enthalpy, that is $$\Delta H$$, is known as:
  • precipitation reaction
  • acid-base neutralization
  • thermochemical reaction
  • oxidation-reduction reaction
A piece of ice kept at room temperature melts of its own. This reaction is governed by which law?
  • Second law of thermodynamics
  • First law of thermodynamics
  • Third law of thermodynamics
  • Zeroth law of thermodynamics
Carbon reacts with Sulphur to give carbon disulphide, which is an endothermic reaction, where $$92kJ/mol$$ of heat is absorbed. What will be the value of $$\Delta H$$, when $$24$$ grams of carbon reacts?
  • $$-92kJ$$
  • $$+92kJ$$
  • $$-184kJ$$
  • $$+184kJ$$
ln which of the processes, does the internal energy of the system remain constant?
  • Adiabatic
  • Isochoric
  • Isobaric
  • Isothermal
Given, sublimation and ionization energy of $$Na$$ are $$107\space kJ/mol$$ and $$502 \space kJ/mol$$ respectively and bond dissociation energy required for chlorine gas and its electron affinity energy are $$121\space kJ/mol$$ and $$-355\space kJ/mol$$. If $$\triangle H_{f}^{0}$$ is $$-411\space kJ/mol$$. What is its approximate lattice enthalpy?
  • $$-786\space kJ/mol$$
  • $$788\space kJ/mol$$
  • $$388\space kJ/mol$$
  • $$-508\space kJ/mol$$
For a thermodynamics process to be reversible, the temperature difference between hot body and the working substance should be 
  • zero
  • minimunm
  • maximum
  • infinity
Thermochemical equation does not indicate the amount of heat evolved or absorbed.
  • True
  • False
In a thermodynamic process, a system absorbs 2 k cal of heat and at the same time does 800 J of work. The change in internal energy of the system is
  • 7600 J
  • 2000 J
  • 4800 J
  • -7600 J
Consider the following processes $$\triangle H(kJ/mol)$$
$$\dfrac {1}{2}A\rightarrow B + 150$$
$$3B \Rightarrow 2C + D - 125$$
$$E + A \rightarrow 2D + 350$$
For $$B + D \rightarrow E + 2C, \triangle H$$ will be:
  • $$+525\ kJ/mol$$
  • $$-175\ kJ/mol$$
  • $$-325\ kJ/mol$$
  • $$+325\ kJ/mol$$
Which of the properties are suitable for a cooking utensil?
  • High specific heat
  • Low specific heat
  • High conductivity
  • Low conductivity
Consider the following changes
$$M\left( s \right) \longrightarrow M\left( g \right) $$     ...(1)
$$M\left( g \right) \longrightarrow { M }^{ 2+ }\left( g \right) +2{ e }^{ - }$$     ....(2)
$$M\left( g \right) \longrightarrow { M }^{ + }\left( g \right) +{ e }^{ - }$$     ....(3)
$${ M }^{ + }\left( g \right) \longrightarrow { M }^{ 2+ }\left( g \right) +{ e }^{ - }$$    ...(4)
$$M\left( g \right) \longrightarrow { M }^{ 2+ }\left( g \right) +2{ e }^{ - }$$    ...(5)
The second ionisation energy of $$M$$ could be determined from the energy values associated with:
  • $$1+2+4$$
  • $$1+5-3$$
  • $$2+3-4$$
  • $$5-3$$
Thermodynamic condition for irreversible spontaneous process at constant '$$T$$' and '$$P$$' is:
  • $$\Delta G< 0$$
  • $$\Delta G=0$$
  • $$\Delta G> 0$$
  • Both (B) and (C)
What is the thermodynamic condition for the feasibility of a process?
  • $$(\Delta S)_{sys} > 0$$
  • $$(\Delta G)_{sys} > 0$$
  • $$(\Delta S)_{sys} + (\Delta S)_{surr} > 0$$
  • $$(\Delta G)_{sys} + (\Delta G)_{surr} < 0$$
Specific heat of a substance can be :
  • zero
  • positive
  • infinity
  • negative
For the reaction $$N_2+3X_2 \rightarrow 2NX_3$$ where $$X = F, Cl$$ (the average bond energies are $$F-F = 155 \ kJ \ mol^{-1}$$, $$N-F = 272 \  kJ \ mol^{-1}$$, $$Cl-Cl=242\ kJ \ mol^{-1}$$ , $$N-Cl=200\  kJ \ mol^{-1}$$ and $$N \equiv N = 941 kJ\, mol^{-1}$$). The heats of formation of $$NF_3$$ and $$NCl_3$$ in $$kJ\ mol^{-1}$$, respectively, are closest to:
  • $$- 226$$ and $$+ 467$$
  • $$+ 226$$ and $$-467$$
  • $$-151$$ and $$+ 311$$
  • $$+ 151$$ and $$-311$$
Which of the following processes is always non - feasible?
  • $$\Delta H > 0, \Delta S > 0$$
  • $$\Delta H < 0, \Delta S > 0$$
  • $$\Delta H > 0, \Delta S < 0$$
  • $$\Delta H < 0, \Delta S < 0$$
For a chemical reaction, $$\Delta S = - 0.035\  kJ/K$$ and $$\Delta H = - 20k J$$. At what temperature does the reaction turn non-spontaneous?
  • $$<5.14\ K$$
  • $$<57.14\ K$$
  • $$<571.4\ K$$
  • $$<5714.0\ K$$

Consider the Born-Haber cycle for the formation of an ionic compound given below and identify the compound $$\left(Z\right)$$ formed.
638756_7d967d3ca6c44d53a99f771d431495b4.png
  • $${M}^{+}{X}^{-}$$
  • $${M}^{-}{X}_{\left(s\right)}^{-}$$
  • $$MX$$
  • $${M}^{+}{X}_{\left(g\right)}^{-}$$
The criterion for a spontaneous process is :
  • $$\triangle G > 0$$
  • $$\triangle G < 0$$
  • $$\triangle G = 0$$
  • $$\triangle S_{total} < 0$$
If enthalpies of formation for $$C_2H_4(g)$$, $$CO_2(g)$$ and $$H_2O(l)$$ at $$25^o$$C and $$1$$ atm pressure be $$52$$, $$-394$$ and $$-286$$ $$kJ \ mol^{-1}$$ respectively, then the enthalpy of combustion of $$C_2H_4(g)$$ will be:
  • $$-141.2$$kJ $$mol^{-1}$$
  • $$-1412$$kJ $$mol^{-1}$$
  • $$+141.2$$kJ $$mol^{-1}$$
  • $$+1412$$kJ $$mol^{-1}$$
What is the enthalpy of the disproportion of MgCl if the enthalpy of formation of hypothetical MgCl is -125 kJ/mol and the $$MgCl_2$$ is -642  kJ mol$$^{ -1 }$$?
  • -767  kJ mol$$^{ -1 }$$. 
  • 767 kJ mol$$^{ -1 }$$. 
  • -392  kJ mol$$^{ -1 }$$. 
  • 392  kJ mol$$^{ -1 }$$. 
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