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4

Consider the reaction, C + O2 CO2; ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 → C + O2?

A. -94 kcal

B. +94 kcal

C. > 94 kcal

D. < -94 kcal

Correct Answer :

B. +94 kcal


Related Questions

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4

Pick out the correct statement.

A. Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero

B. Melting of ice involves increase in enthalpy and a decrease in randomness

C. The internal energy of an ideal gas depends only on its pressure

D. Maximum work is done under reversible conditions

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4

Number of phases in a colloidal system is:

A. 1

B. 2

C. 3

D. 4

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4

In Joule-Thomson porous plug experiment, the

A. Enthalpy does not remain constant

B. Entire apparatus is exposed to surroundings

C. Temperature remains constant

D. None of these

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4

Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the

A. Cold reservoir approaches zero

B. Hot reservoir approaches infinity

C. Either (A) or (B)

D. Neither (A) nor (B)

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4

In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants)

A. Addition of inert gas favours the forward reaction, when Δx is positive

B. Pressure has no effect on equilibrium, when Δn = 0

C. Addition of inert gas has no effect on the equilibrium constant at constant volume for any value of Δx (+ ve, - ve) or zero)

D. All 'a', 'b' & 'c'

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4

In the reaction, H2 +I2 2HI, addition of an inert gas will

A. Increase the partial pressure of H2

B. Increase the partial pressure of I2

C. Increase the total pressure and hence shift the equilibrium towards the right

D. Not affect the equilibrium conditions

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High __________ is an undesirable property for a good refrigerant.

A. Specific heat

B. Latent heat of vaporisation

C. Viscosity

D. Specific vapor volume

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In the decomposition of PCl5 represented by, PCl5 PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.

A. Increase

B. Decrease

C. Not alter

D. None of these

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4

Pick out the wrong statement.

A. Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point

B. Entropy of a system decreases with the evolution of heat

C. Change of internal energy is negative for exothermic reactions

D. The eccentric factor for all materials is always more than one

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4

Dryness fraction of wet steam is defined as the ratio of mass of vapour in the mixture to the mass of mixture __________ calorimeter is not used for measuring the dryness fraction of steam.

A. Bomb

B. Separating

C. Bucket

D. Throttling

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4

A Carnot cycle consists of the following steps:

A. Two isothermal and two isentropic

B. Two isobaric and two isothermal

C. Two isochoric and two isobaric

D. Two isothermals and two isochoric

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4

Pick out the wrong statement.

A. A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy.

B. An open system permits exchange of both mass and energy with its surroundings

C. The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics

D. None of the above

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4

Pick out the extensive property out of the following.

A. Surface tension

B. Free energy

C. Specific heat

D. Refractive index

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4

With increase in temperature, the atomic heat capacities of all solid elements

A. Increases

B. Decreases

C. Remains unchanged

D. Decreases linearly

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When a system is in equilibrium for all possible processes, the differential or finite change of entropy is

A. < 0

B. > 0

C. = 0

D. None of these

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For an incompressible fluid, the __________ is a function of both pressure as well as temperature.

A. Internal energy

B. Enthalpy

C. Entropy

D. All (A), (B) & (C)

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4

Number of degrees of freedom for a three phase system in equilibrium comprising of three nonreacting chemical species is

A. 2

B. 0

C. 1

D. 3

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4

Pick out the wrong statement.

A. The net change in entropy in any reversible cycle is always zero

B. The entropy of the system as a whole in an irreversible process increases

C. The entropy of the universe tends to a maximum

D. The entropy of a substance does not remain constant during a reversible adiabatic change

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4

The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is

A. 0

B. +ve

C. -ve

D.

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4

Specific/molar Gibbs free energy for a pure substance does not change during

A. Sublimation

B. Vaporisation

C. Melting

D. Either (A), (B) or (C)

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4

At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is

A. Zero

B. One

C. Infinity

D. Negative

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As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches

A. Zero

B. Unity

C. Infinity

D. An indeterminate value

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4

Compressibility factor of a gas is

A. Not a function of its pressure

B. Not a function of its nature

C. Not a function of its temperature

D. Unity, if it follows PV = nRT

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4

Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will

A. Increase

B. Decrease

C. Remain unchanged

D. First fall and then rise

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4

Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?

A. Freon

B. Liquid sulphur dioxide

C. Methyl chloride

D. Ammonia

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Which of the following has the least thermal efficiency?

A. Steam engine

B. Carnot engine

C. Diesel engine

D. Otto engine

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Which of the following is not an intensive property?

A. Chemical potential

B. Surface tension

C. Heat capacity

D. None of these

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A refrigerator works on the principle of __________ law of thermodynamics.

A. Zeroth

B. First

C. Second

D. Third

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The equilibrium constant for a chemical reaction at two different temperatures is given by

A. Kp2/Kp1 = - (ΔH/R) (1/T2 - 1/T1)

B. Kp2/Kp1 = (ΔH/R) (1/T2 - 1/T1)

C. Kp2/Kp1 = ΔH (1/T2 - 1/T1)

D. Kp2/Kp1 = - (1/R) (1/T2 - 1/T1)

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Chemical potential is a/an

A. Extensive property

B. Intensive property

C. Force which drives the chemical system to equilibrium

D. Both (B) and (C)