Thermodynamics
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<p><strong>33. Which one is the correct unit for entropy?</strong></p>
<p><strong>(a) </strong>KJ mol </p>
<p><strong>(b)</strong> JK mol</p>
<p><strong>(c) </strong>JK mol<sup>-1 <strong> </strong></sup><strong> </strong></p>
<p><strong>(</strong><strong>d) </strong>KJ mol<sup>-1</sup></p>
31. An isochoric and isobaric process takes place at constant
(a) Temperature and pressure respectively
(b) Pressure and concentration respectively
(c) Volume and pressure respectively
(d) Concentration and temperature respectively
31. An isochoric and isobaric process takes place at constant
(a) Temperature and pressure respectively
(b) Pressure and concentration respectively
(c) Volume and pressure respectively
(d) Concentration and temperature respectively
31. (c) Volume and pressure respectively
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29. Which of the following statements is incorrect?
(a) Entropy is a measure of disorder or randomness.
(b) First law of thermodynamics does not guide us about the direction of chemical reactions
(c) Variables like p, V, T are called state variables or state functions.
(d) The state of the surroundings can always be completely specified.
29. Which of the following statements is incorrect?
(a) Entropy is a measure of disorder or randomness.
(b) First law of thermodynamics does not guide us about the direction of chemical reactions
(c) Variables like p, V, T are called state variables or state functions.
(d) The state of the surroundings can always be completely specified.
28. Reaction spontaneous at all temperatures when:
(a) ΔrH? is negative, ΔrS? positive, ΔrG? is negative.
(b) ΔrH? is positive, ΔrS? positive, ΔrG? is negative.
(c) ΔrH? is negative, ΔrS? positive, ΔrG? is positive.
(d) ΔrH? is positive, ΔrS? positive, ΔrG? is positive.
28. Reaction spontaneous at all temperatures when:
(a) ΔrH? is negative, ΔrS? positive, ΔrG? is negative.
(b) ΔrH? is positive, ΔrS? positive, ΔrG? is negative.
(c) ΔrH? is negative, ΔrS? positive, ΔrG? is positive.
(d) ΔrH? is positive, ΔrS? positive, ΔrG? is positive.
28. (a) ΔrH? is negative, ΔrS? positive, ΔrG? is negative.
Upvote 27. Assertion: It requires less heat to vaporise 1 mol of acetone than it does to vaporize 1 mol of water.
Reason: For an organic liquid, such as acetone, the intermolecular dipole-dipole interactions are significantly weaker.
27. Assertion: It requires less heat to vaporise 1 mol of acetone than it does to vaporize 1 mol of water.
Reason: For an organic liquid, such as acetone, the intermolecular dipole-dipole interactions are significantly weaker.
27. (a) The magnitude of the enthalpy change depends on the strength of the intermolecular interactions in the substance undergoing the phase transformations. For example, the strong hydrogen bonds between water molecules hold them tightly in liquid phase. For an organic liquid, such as aceton
Upvote 26. Assertion: When temperature of a crystalline solid is increased, the degree of randomness of its constituents increases.
Reason:The entropy of any pure crystalline substance approaches zero as the temperature approaches absolute zero.
26. Assertion: When temperature of a crystalline solid is increased, the degree of randomness of its constituents increases.
Reason:The entropy of any pure crystalline substance approaches zero as the temperature approaches absolute zero.
26. (b) A system at higher temperature has greater randomness in it than one at lower temperature. Thus, temperature is the measure of average chaotic motion of particles in the system.
Upvote 25. Assertion: Entropy decreases when a liquid crystallizes into solid.
Reason: Molecules tend to be in a less ordered state.
25. Assertion: Entropy decreases when a liquid crystallizes into solid.
Reason: Molecules tend to be in a less ordered state.
25. (c) When a liquid crystallizes into solid or after freezing, the molecules attain an ordered state and therefore, entropy decreases.
Upvote 24. Assertion: In an exothermic reaction, heat is evolved, and system gains heat from the surroundings.
Reason: qp and ΔrH will also be negative.
24. Assertion: In an exothermic reaction, heat is evolved, and system gains heat from the surroundings.
Reason: qp and ΔrH will also be negative.
24. (d) In an exothermic reaction, heat is evolved, and system loses heat to the surroundings. Therefore, qp will be negative and ΔrH will also be negative. Similarly in an endothermic reaction, heat is absorbed, qp is positive and ΔrH will be positive.
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