Q. What is the unit of enthalpy?
A.
Joules per mole (J/mol)
B.
Calories per mole (cal/mol)
C.
Both A and B
D.
Liters per mole (L/mol)
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Solution
Enthalpy can be expressed in both Joules per mole and Calories per mole.
Correct Answer: C — Both A and B
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Q. What is the unit of entropy?
A.
J/mol·K
B.
J/K
C.
K
D.
J/mol
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Solution
The unit of entropy is Joules per mole per Kelvin (J/mol·K).
Correct Answer: A — J/mol·K
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Q. What is the work done by a gas during an isothermal expansion from volume Vi to Vf?
A.
nRT ln(Vf/Vi)
B.
nR(Tf - Ti)
C.
Zero
D.
nRT
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Solution
The work done by a gas during an isothermal expansion is W = nRT ln(Vf/Vi).
Correct Answer: A — nRT ln(Vf/Vi)
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Q. What is the work done by an ideal gas during an isothermal expansion from volume Vi to Vf?
A.
nRT ln(Vf/Vi)
B.
nR(Tf - Ti)
C.
Zero
D.
nRT
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Solution
The work done by an ideal gas during an isothermal expansion is W = nRT ln(Vf/Vi).
Correct Answer: A — nRT ln(Vf/Vi)
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Q. Which factor does NOT affect the Gibbs Free Energy of a reaction?
A.
Temperature
B.
Pressure
C.
Concentration of reactants
D.
Nature of the solvent
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Solution
The nature of the solvent does not directly affect the Gibbs Free Energy of a reaction; it is primarily influenced by temperature, pressure, and concentration.
Correct Answer: D — Nature of the solvent
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Q. Which factor does NOT affect the Gibbs Free Energy of a system?
A.
Temperature
B.
Pressure
C.
Concentration of reactants
D.
Nature of the solvent
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Solution
While temperature, pressure, and concentration of reactants affect Gibbs Free Energy, the nature of the solvent does not directly affect ΔG.
Correct Answer: D — Nature of the solvent
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Q. Which law states that energy cannot be created or destroyed?
A.
Zeroth law
B.
First law
C.
Second law
D.
Third law
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Solution
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed.
Correct Answer: B — First law
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Q. Which law states that the total enthalpy change for a reaction is the same, regardless of the number of steps taken?
A.
First Law of Thermodynamics
B.
Second Law of Thermodynamics
C.
Hess's Law
D.
Gibbs Free Energy
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Solution
Hess's Law states that the total enthalpy change for a reaction is the same, regardless of the number of steps taken.
Correct Answer: C — Hess's Law
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Q. Which law states that the total enthalpy change for a reaction is the same, regardless of the number of steps in the reaction?
A.
First Law of Thermodynamics
B.
Second Law of Thermodynamics
C.
Hess's Law
D.
Gibbs Free Energy
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Solution
Hess's Law states that the total enthalpy change for a reaction is the same, regardless of the number of steps in the reaction.
Correct Answer: C — Hess's Law
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Q. Which law states that the total entropy of an isolated system can never decrease over time?
A.
Zeroth Law
B.
First Law
C.
Second Law
D.
Third Law
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Solution
The Second Law of Thermodynamics states that the total entropy of an isolated system can never decrease over time.
Correct Answer: C — Second Law
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Q. Which of the following conditions will favor the spontaneity of a reaction?
A.
High ΔH and low ΔS
B.
Low ΔH and high ΔS
C.
High ΔH and high ΔS
D.
Low ΔH and low ΔS
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Solution
A reaction is favored when it has low ΔH (exothermic) and high ΔS (increased disorder).
Correct Answer: B — Low ΔH and high ΔS
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Q. Which of the following conditions will lead to a decrease in Gibbs Free Energy?
A.
Increasing temperature for an exothermic reaction.
B.
Decreasing entropy.
C.
Increasing pressure for a gas-phase reaction.
D.
Increasing ΔH.
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Solution
Increasing temperature for an exothermic reaction (ΔH < 0) can lead to a decrease in Gibbs Free Energy, making the reaction more spontaneous.
Correct Answer: A — Increasing temperature for an exothermic reaction.
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Q. Which of the following conditions will lead to a negative ΔG?
A.
High temperature and low ΔH
B.
Low temperature and high ΔH
C.
High temperature and high ΔS
D.
Low temperature and low ΔS
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Solution
A high temperature and high ΔS will favor a negative ΔG, making the process spontaneous.
Correct Answer: C — High temperature and high ΔS
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Q. Which of the following conditions will lead to a positive ΔG?
A.
High temperature and low entropy.
B.
Low temperature and high enthalpy.
C.
High temperature and high entropy.
D.
Low temperature and low enthalpy.
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Solution
A positive ΔG can occur at low temperatures when the enthalpy is high, making the reaction non-spontaneous.
Correct Answer: B — Low temperature and high enthalpy.
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Q. Which of the following conditions will lead to a spontaneous reaction?
A.
ΔH > 0 and ΔS < 0
B.
ΔH < 0 and ΔS > 0
C.
ΔH > 0 and ΔS > 0
D.
ΔH < 0 and ΔS < 0
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Solution
A spontaneous reaction occurs when ΔG < 0. This is true for ΔH < 0 and ΔS > 0, as it leads to a negative ΔG.
Correct Answer: B — ΔH < 0 and ΔS > 0
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Q. Which of the following equations relates Gibbs Free Energy to enthalpy and entropy?
A.
ΔG = ΔH - TΔS
B.
ΔG = TΔS - ΔH
C.
ΔG = ΔH + TΔS
D.
ΔG = ΔH / T + ΔS
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Solution
The correct relation is ΔG = ΔH - TΔS.
Correct Answer: A — ΔG = ΔH - TΔS
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Q. Which of the following expressions correctly relates ΔG, ΔH, and ΔS?
A.
ΔG = ΔH + TΔS
B.
ΔG = ΔH - TΔS
C.
ΔG = TΔS - ΔH
D.
ΔG = ΔH + ΔS
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Solution
The correct relation is ΔG = ΔH - TΔS.
Correct Answer: B — ΔG = ΔH - TΔS
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Q. Which of the following factors does NOT affect Gibbs Free Energy?
A.
Temperature
B.
Pressure
C.
Concentration of reactants
D.
Nature of the solvent
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Solution
The nature of the solvent does not directly affect Gibbs Free Energy; it is primarily influenced by temperature, pressure, and concentration.
Correct Answer: D — Nature of the solvent
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Q. Which of the following factors does NOT affect the enthalpy change of a reaction?
A.
Nature of reactants
B.
Temperature
C.
Pressure
D.
Pathway of the reaction
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Solution
The enthalpy change of a reaction is independent of the pathway taken, as it is a state function.
Correct Answer: D — Pathway of the reaction
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Q. Which of the following factors does NOT affect the entropy of a system?
A.
Temperature
B.
Volume
C.
Pressure
D.
Nature of the substance
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Solution
While temperature, volume, and the nature of the substance affect entropy, pressure does not directly affect the entropy of a system in a significant way.
Correct Answer: C — Pressure
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Q. Which of the following factors does NOT affect the Gibbs Free Energy of a system?
A.
Temperature
B.
Pressure
C.
Concentration of reactants
D.
Nature of the solvent
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Solution
While temperature, pressure, and concentration of reactants affect Gibbs Free Energy, the nature of the solvent does not directly affect ΔG.
Correct Answer: D — Nature of the solvent
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Q. Which of the following has the highest enthalpy of formation?
A.
O2(g)
B.
H2(g)
C.
C(s)
D.
CO2(g)
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Solution
CO2(g) has a higher enthalpy of formation compared to the elements in their standard states.
Correct Answer: D — CO2(g)
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Q. Which of the following has the highest entropy at 25°C?
A.
Ice
B.
Water
C.
Steam
D.
All have the same entropy
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Solution
Steam has the highest entropy at 25°C because it is in the gaseous state, which has more disorder compared to solid (ice) and liquid (water).
Correct Answer: C — Steam
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Q. Which of the following has the highest entropy at 298 K?
A.
Ice (solid H2O)
B.
Liquid water (H2O)
C.
Water vapor (H2O(g))
D.
None of the above
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Solution
Water vapor has the highest entropy because gases have greater disorder compared to liquids and solids.
Correct Answer: C — Water vapor (H2O(g))
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Q. Which of the following has the highest entropy at room temperature?
A.
Solid NaCl
B.
Liquid water
C.
Water vapor
D.
Ice
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Solution
Water vapor has the highest entropy due to its gaseous state, which has more disorder compared to solids and liquids.
Correct Answer: C — Water vapor
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Q. Which of the following has the highest entropy?
A.
Ice at 0 °C
B.
Water at 0 °C
C.
Water vapor at 100 °C
D.
Water at 100 °C
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Solution
Water vapor at 100 °C has the highest entropy due to its gaseous state, which has more disorder compared to the liquid and solid states.
Correct Answer: C — Water vapor at 100 °C
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Q. Which of the following has the highest standard molar entropy (S°) at 298 K?
A.
H2(g)
B.
O2(g)
C.
N2(g)
D.
H2O(l)
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Solution
H2O(l) has a higher standard molar entropy than the diatomic gases due to its molecular complexity and interactions.
Correct Answer: D — H2O(l)
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Q. Which of the following is a correct expression for Gibbs Free Energy?
A.
ΔG = ΔH + TΔS
B.
ΔG = ΔH - TΔS
C.
ΔG = TΔS - ΔH
D.
ΔG = ΔS - ΔH
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Solution
The correct expression for Gibbs Free Energy is ΔG = ΔH - TΔS.
Correct Answer: B — ΔG = ΔH - TΔS
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Q. Which of the following is a correct unit for Gibbs Free Energy?
A.
Joules per mole (J/mol)
B.
Kilojoules (kJ)
C.
Calories (cal)
D.
All of the above
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Solution
Gibbs Free Energy can be expressed in various units, including Joules per mole, kilojoules, and calories.
Correct Answer: D — All of the above
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Q. Which of the following is a state function?
A.
Work
B.
Heat
C.
Enthalpy
D.
All of the above
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Solution
Enthalpy is a state function, while work and heat are not state functions as they depend on the path taken.
Correct Answer: C — Enthalpy
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