Q. What is the energy of the ground state of a hydrogen atom?
A.
-13.6 eV
B.
-3.4 eV
C.
0 eV
D.
13.6 eV
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Solution
The energy of the ground state of a hydrogen atom is -13.6 eV.
Correct Answer: A — -13.6 eV
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Q. What is the energy released in nuclear fusion compared to nuclear fission? (2023)
A.
Less
B.
Equal
C.
More
D.
None
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Solution
The energy released in nuclear fusion is generally more than that released in nuclear fission, making it a powerful energy source.
Correct Answer: C — More
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Q. What is the energy released in nuclear fusion primarily due to? (2023)
A.
Mass defect
B.
Chemical bonds
C.
Nuclear forces
D.
Electromagnetic interactions
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Solution
The energy released in nuclear fusion is primarily due to the mass defect, where the mass of the resulting nucleus is less than the sum of the masses of the individual nucleons.
Correct Answer: A — Mass defect
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Q. What is the energy stored in a capacitor of capacitance 10μF charged to a potential difference of 50V?
A.
0.0125 J
B.
0.025 J
C.
0.05 J
D.
0.1 J
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Solution
U = 1/2 * C * V² = 1/2 * (10 × 10^-6 F) * (50 V)² = 0.0125 J.
Correct Answer: B — 0.025 J
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Q. What is the energy stored in a capacitor of capacitance 4μF charged to 12V? (2022)
A.
24μJ
B.
28.8μJ
C.
48μJ
D.
72μJ
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Solution
The energy stored (U) is given by U = 1/2 CV². Thus, U = 1/2 * 4μF * (12V)² = 288μJ.
Correct Answer: C — 48μJ
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Q. What is the energy stored in a capacitor of capacitance 5μF charged to a potential difference of 10V? (2023)
A.
0.25mJ
B.
0.5mJ
C.
0.75mJ
D.
1mJ
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Solution
Using the formula U = 1/2 CV², we have U = 1/2 * 5μF * (10V)² = 0.5mJ.
Correct Answer: B — 0.5mJ
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Q. What is the energy stored in a capacitor of capacitance C charged to a potential V? (2021)
A.
CV
B.
1/2 CV^2
C.
1/2 QV
D.
QV
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Solution
The energy (U) stored in a capacitor is given by the formula U = 1/2 CV^2.
Correct Answer: B — 1/2 CV^2
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Q. What is the energy stored in a capacitor of capacitance C charged to a voltage V?
A.
1/2 CV
B.
CV
C.
1/2 C/V
D.
C/V
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Solution
The energy (U) stored in a capacitor is given by the formula U = 1/2 CV².
Correct Answer: A — 1/2 CV
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Q. What is the energy stored in a capacitor with capacitance C charged to a voltage V?
A.
1/2 CV²
B.
CV
C.
1/2 V²/C
D.
C²V
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Solution
The energy (U) stored in a capacitor is given by the formula U = 1/2 CV².
Correct Answer: A — 1/2 CV²
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Q. What is the energy stored in a capacitor with capacitance C charged to voltage V?
A.
1/2 CV
B.
CV
C.
1/2 C/V
D.
C/V
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Solution
The energy (U) stored in a capacitor is given by the formula U = 1/2 CV².
Correct Answer: A — 1/2 CV
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Q. What is the enthalpy change for the formation of 1 mole of CO2 from its elements in their standard states?
A.
-393.5 kJ/mol
B.
-285.8 kJ/mol
C.
0 kJ/mol
D.
100 kJ/mol
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Solution
The standard enthalpy of formation of CO2 is -393.5 kJ/mol.
Correct Answer: A — -393.5 kJ/mol
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Q. What is the enthalpy change for the formation of water from hydrogen and oxygen?
A.
It is positive.
B.
It is negative.
C.
It is zero.
D.
It is undefined.
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Solution
The formation of water from hydrogen and oxygen is an exothermic reaction, resulting in a negative enthalpy change.
Correct Answer: B — It is negative.
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Q. What is the enthalpy change for the reaction 2Na + Cl2 → 2NaCl?
A.
-411 kJ
B.
-240 kJ
C.
0 kJ
D.
411 kJ
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Solution
The enthalpy change for the formation of NaCl from its elements is -411 kJ.
Correct Answer: A — -411 kJ
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Q. What is the enthalpy change for the reaction at constant pressure?
A.
ΔH = ΔU + PΔV
B.
ΔH = ΔU - PΔV
C.
ΔH = ΔU + VΔP
D.
ΔH = ΔU - VΔP
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Solution
At constant pressure, the enthalpy change is given by ΔH = ΔU + PΔV.
Correct Answer: A — ΔH = ΔU + PΔV
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Q. What is the enthalpy change for the reaction N2(g) + 3H2(g) → 2NH3(g) at standard conditions?
A.
-92.4 kJ
B.
-45.9 kJ
C.
0 kJ
D.
0.5 kJ
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Solution
The standard enthalpy change for the formation of ammonia is -92.4 kJ.
Correct Answer: A — -92.4 kJ
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Q. What is the enthalpy change for the reaction: 2H2(g) + O2(g) → 2H2O(g)?
A.
It is positive.
B.
It is negative.
C.
It is zero.
D.
It is dependent on temperature.
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Solution
The formation of water from hydrogen and oxygen is an exothermic reaction, thus the enthalpy change is negative.
Correct Answer: B — It is negative.
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Q. What is the enthalpy change for the reaction: 2H2(g) + O2(g) → 2H2O(l)?
A.
-571.6 kJ
B.
-285.8 kJ
C.
0 kJ
D.
285.8 kJ
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Solution
The enthalpy change for the formation of 2 moles of water is -571.6 kJ.
Correct Answer: A — -571.6 kJ
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Q. What is the enthalpy change for the reaction: C(s) + O2(g) -> CO2(g)?
A.
-393.5 kJ/mol
B.
-241.8 kJ/mol
C.
0 kJ/mol
D.
285.8 kJ/mol
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Solution
The enthalpy change for the formation of CO2 from carbon and oxygen is -393.5 kJ/mol.
Correct Answer: A — -393.5 kJ/mol
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Q. What is the enthalpy change for the reaction: C(s) + O2(g) → CO2(g)?
A.
-393.5 kJ/mol
B.
-241.8 kJ/mol
C.
0 kJ/mol
D.
285.8 kJ/mol
Show solution
Solution
The enthalpy change for the formation of CO2 from its elements is -393.5 kJ/mol.
Correct Answer: A — -393.5 kJ/mol
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Q. What is the enthalpy change for the reaction: CaCO3(s) → CaO(s) + CO2(g)?
A.
It is an endothermic reaction.
B.
It is an exothermic reaction.
C.
It has no enthalpy change.
D.
It is spontaneous at all temperatures.
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Solution
The decomposition of calcium carbonate is an endothermic reaction, requiring heat input.
Correct Answer: A — It is an endothermic reaction.
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Q. What is the enthalpy change for the reaction: H2(g) + 1/2 O2(g) → H2O(l)?
A.
-285.8 kJ/mol
B.
0 kJ/mol
C.
-241.8 kJ/mol
D.
-572 kJ/mol
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Solution
The standard enthalpy change for the formation of water from its elements is -241.8 kJ/mol.
Correct Answer: C — -241.8 kJ/mol
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Q. What is the enthalpy change for the reaction: N2(g) + 3H2(g) → 2NH3(g)?
A.
It is always positive.
B.
It is always negative.
C.
It can be either positive or negative depending on conditions.
D.
It is zero.
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Solution
The formation of ammonia from nitrogen and hydrogen is an exothermic reaction, thus the enthalpy change is negative.
Correct Answer: B — It is always negative.
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Q. What is the enthalpy change when 1 mole of NaCl is dissolved in water?
A.
-3.87 kJ
B.
0 kJ
C.
+3.87 kJ
D.
-7.0 kJ
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Solution
The enthalpy change when 1 mole of NaCl is dissolved in water is approximately -3.87 kJ.
Correct Answer: A — -3.87 kJ
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Q. What is the enthalpy change when 1 mole of water vapor condenses to liquid water?
A.
It is positive.
B.
It is negative.
C.
It is zero.
D.
It is dependent on pressure.
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Solution
The condensation of water vapor to liquid water releases heat, making the enthalpy change negative.
Correct Answer: B — It is negative.
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Q. What is the entropy change for a reversible isothermal expansion of an ideal gas?
A.
nR ln(Vf/Vi)
B.
0
C.
nR(Tf - Ti)
D.
nC ln(Vf/Vi)
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Solution
The entropy change for a reversible isothermal expansion of an ideal gas is ΔS = nR ln(Vf/Vi).
Correct Answer: A — nR ln(Vf/Vi)
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Q. What is the entropy change for a reversible isothermal process?
A.
Zero
B.
nR ln(Vf/Vi)
C.
nR(Tf - Ti)
D.
nR ln(Tf/Ti)
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Solution
The entropy change for a reversible isothermal process is ΔS = nR ln(Vf/Vi).
Correct Answer: B — nR ln(Vf/Vi)
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Q. What is the entropy change for a reversible process?
A.
Always positive
B.
Always negative
C.
Can be zero
D.
Depends on the path taken
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Solution
For a reversible process, the entropy change can be zero if the process is isothermal and reversible.
Correct Answer: C — Can be zero
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Q. What is the entropy change for a system that undergoes a phase transition at constant temperature?
A.
ΔS = 0
B.
ΔS = Q/T
C.
ΔS = T/Q
D.
ΔS = Q + T
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Solution
During a phase transition at constant temperature, the change in entropy is given by ΔS = Q/T, where Q is the heat absorbed or released.
Correct Answer: B — ΔS = Q/T
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Q. What is the entropy change for an ideal gas during an isothermal expansion?
A.
Zero
B.
nR ln(Vf/Vi)
C.
nC_v ln(Tf/Ti)
D.
nC_p ln(Tf/Ti)
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Solution
The entropy change for an ideal gas during an isothermal expansion is ΔS = nR ln(Vf/Vi).
Correct Answer: B — nR ln(Vf/Vi)
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Q. What is the entropy change for the isothermal expansion of an ideal gas from volume V1 to V2 at temperature T?
A.
R ln(V2/V1)
B.
R (V2 - V1)/T
C.
0
D.
R (V1/V2)
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Solution
The entropy change for an isothermal expansion is given by ΔS = nR ln(V2/V1). For 1 mole, ΔS = R ln(V2/V1).
Correct Answer: A — R ln(V2/V1)
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