For which of the following changes ∆ H ≠ ∆ E ?

H C l + N a O H → N a C l + H 2 O

C ( s ) + O 2 ( g ) ⇌ C O 2 ( g )

Chemistry - Thermodynamics - Quiz-10

Plants and living beings are examples of -

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Isolated system.
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Adiabatic system.
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Open system.
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Closed system.

For an adiabatic expansion of a perfect gas, $∆$ P/P is equal to?

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$\frac{∆ V}{V}$
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$- y \frac{∆ V}{V}$
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$y \frac{∆ V}{V}$
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$- y^{2} \frac{∆ V}{V}$

If a gas at constant temperature and pressure expands,

then its

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Internal energy decreases
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Entropy increases and then decreases
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Internal energy increases
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Internal energy remains constant

If a gas absorbs 200 J of heat and expands by 500 ${cm}^{3}$ against the constant pressure of

2x $10^{5}$ Nm^-2 , then a change in internal energy is -

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+100J
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+ 300J
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$-$ 200 J
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$-$ 100J

The internal energy of a substance does not depend upon

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Translational energy
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Vibrational energy
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Energy due to the gravitational pull
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Rotational energy

Internal energy (E) and pressure of a gas of unit volume are related

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$P = \frac{2}{3} E$
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$P = \frac{3}{2} E$
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$P = \frac{E}{2}$
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P=2E

Which one of the following statements is false?

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Temperature is a state function.
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Work is a state function.
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Change in the state is completely defined when the initial and final states are specified.
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Work appears at the boundary of the system.

Considering entropy (S) as a thermodynamic parameter, the

criterion for the spontaneity of any process is

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$∆ S_{s y s t e m} + ∆ S_{s u r r o u n d i n g s} > 0$
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$∆ S_{s y s t e m} - ∆ S_{s u r r o u n d i n g s} > 0$
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$∆ S_{s y s t e m} > 0$
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$∆ S_{s y s t e m} > 0$

For which of the following processes will the entropy increase?

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Reaction of magnesium with oxygen to form magnesium oxide
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Reaction of nitrogen and hydrogen to form ammonia
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Sublimation of dry ice
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Condensation of steam

Which of the following is the correct first law thermodynamics equation?

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$U = ∆ Q - W$
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$∆ W = ∆ U + ∆ Q$
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$∆ U = ∆ W + ∆ Q$
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None of these

Which of the following conditions result in a spontaneous reaction?

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Exothermic and increasing disorder
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Exothermic and decreasing disorder
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Endothermic and increasing disorder
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Endothermic and decreasing disorder

Assume each reaction is carried out in an open container. For which of the following reactions will $∆ H be equal to ∆ U ?$

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${PCl}_{3} (g) \to {PCl}_{3} (g) + {Cl}_{2} (g)$
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$2 CO (g) + O_{2} (g) \to 2 {CO}_{2} (g)$
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$H_{2} (g) + {Br}_{2} (g) \to 2 HBr (g)$
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$C (s) + 2 H_{2} O (g) \to 2 H_{2} (g) + {CO}_{2} (g)$

ldentify the correct statement regarding entropy.

substance is +ve.

substance is taken to be zero

in taken to be 0.

be 0.

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At absolute zero temperature, entropy of a perfectly crystaline
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At absolute zero temperature, entropy of a perfectly crystalline
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At absolute zero temperature, entropy of all crystaline sustances
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At 0 $°$ C entropy of a perfectly crystalline substance is taken to

The reaction that has a value of $∆ S °$ greater than zero among the following is-

$\begin{align}& {{1}{.}\;{CaO}\left({s}\right){+}{CO}_{2}\rightarrow{CaCO}_{3}\left({s}\right)}\\& {{2}{.}\;{NaCl}\left({aq}\right)\rightarrow{NaCl}\left({s}\right)}\\& {{3}{.}\;{NaNO}_{3}\left({s}\right)\rightarrow{Na}^{{+}}\left({aq}\right){+}{NO}_{3}^{{-}}\left({aq}\right)}\\& {{4}{.}\;{N}_{2}\left({g}\right){+}{3}{H}_{2}\left({g}\right)\rightarrow{2}{NH}_{3}\left({g}\right)}\end{align}$

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1
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2
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3
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4

The net work done for an ideal gas is given as

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$-$ 3PV
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3PV
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PV
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Zero

For a spontaneous process, the correct statement is

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Entropy of the system always increases
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Free energy of the system always increases
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Total entropy change is always negative
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Total entropy change is always positive

Which one of the following has the maximum entropy of vaporization?

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water (l)
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toluene (l)
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diethyl ether (l)
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acetone (l)

Which of the following is not an endothermic reaction?

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Combustion of methane
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Decomposition of water
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Dehydrogenation of ethane or ethylene
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Conversion of graphite to diamond

Standard molar enthalpy of formation of ${CO}_{2}$ is equal to

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Zero
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The standard molar enthalpy of combustion of gaseous carbon.
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The sum of standard molar enthalpies of formation Of CO and ${CO}_{2}$
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The standard molar enthalpy of combustion of carbon (graphite)

For which of the following changes

$∆ H \neq ∆ E ?$

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$H_{2} + l_{2} ⇌ 2 H l$
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$H C l + N a O H \to N a C l + H_{2} O$
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$C (s) + O_{2} (g) ⇌ C O_{2} (g)$
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$N_{2} + 3 H_{2} \to 2 N H_{3}$

The Gibbs free energy is defined as

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G=H $-$ T.S
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G=H+T.S
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G=E $-$ T.S
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G=E+ T.s

Which of the following statement is true for $∆$ G?

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It is always proportional to $∆$ H
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It may be less than or greater than or equal to $∆$ H
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It is always greater than $∆$ H
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It is always less than $∆$ H

The free energy change $(∆ G °)$ is negative when -

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The surroundings do no electrical work on the system.
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The surroundings do electrical work on the system.
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The system does electrical work on the surroundings.
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The system does no electrical work on the surroundings.

In a constant volume calorimeter 3.5g of a gas

(mol.wt.28) was burnt in excess O $_{2}$ at 298 K. The

increase in temperature is 0.45 K due to combus-

tion, If Heat capacity of calorimeter is 2.5 J/K

the value of $∆$ E is

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90 KJ/m
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9 kJ/m
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45 kJ/m
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18 kJ/m

The amount of heat required to raise the temperature of one mole of the substance through 1 K is called, its

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Molar heat
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Entropy
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Thermal capacity
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Specific heat

At standard conditions, if the change in the enthalpy for the following reaction is –109 kJ ${mol}^{- 1}$

$H_{2 (g)} + {Br}_{2 (g)} \to 2 {HBr}_{(g)}$

Given that the bond energy of H 2 and Br 2 is 435 kJ ${mol}^{- 1}$ and 192 kJ ${mol}^{- 1}$ , respectively, what is the bond energy (in kJ ${mol}^{- 1}$ ) of HBr?

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368
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736
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518
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259

$∆_{lattice} H^{⊝}$ or U for NaBr is :

${Given : ∆}_{sub} H^{⊝}$ for sodium metal $= 108.4 kJ {mol}^{- 1}$ , ionisation enthalpy of sodium $= 496 kJ {mol}^{- 1}$ , electron gain enthalpy of bromine $= - 325 kJ {mol}^{- 1}$ , bond dissociation enthalpy of bromine $= 192 kJ {mol}^{- 1}$ , $∆_{f} H^{⊝}$ for NaBr(s) $= - 360.1 kJ {mol}^{- 1}$

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$+ 735.5 kJ {mol}^{- 1}$
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$+ 435.5 kJ {mol}^{- 1}$
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$+ 489.5 kJ {mol}^{- 1}$
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$+ 230.5 kJ {mol}^{- 1}$

The enthalpy of combustion of methane, graphite, and dihydrogen at 298 K are,

–890.3 kJ mol^-1 , –393.5 kJ mol^-1, and –285.8 kJ mol^-1 respectively.

The enthalpy of formation of CH₄(g) is-

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–74.8 kJ mol^-1
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–52.27 kJ mol^-1
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+74.8 kJ mol^-1
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+52.26 kJ mol^-1

For the reaction A + B → C + D + q (kJ/mol), entropy change is positive. The reaction will be

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Possible only at high temperature
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Possible only at low temperature
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Not possible at any temperature
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Possible at any temperature

For the reaction, $2 C l_{(g)} \to C l_{2 (g)}$ , the value of ∆H and ∆S are respectively -

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$∆ H = 0, ∆ S = - ve$
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$∆ H = 0, ∆ S = 0$
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$∆ H = - ve, ∆ S = - ve$
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$∆ H = + ve, ∆ S = + ve$

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Practice Chemistry Quiz Questions and Answers

0:0:1

Practice Chemistry Quiz Questions and Answers

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