Q. In the photoelectric effect, what happens when the frequency of incident light is increased? (2020)
A.
More electrons are emitted
B.
Electrons are emitted with higher energy
C.
No electrons are emitted
D.
The current decreases
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Solution
Increasing the frequency of incident light increases the energy of emitted electrons, as per E = hf.
Correct Answer: B — Electrons are emitted with higher energy
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn2+, what is the oxidation state of zinc after the reaction?
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Solution
Zinc (Zn) is oxidized to Zn2+, so its oxidation state is +2.
Correct Answer: B — +2
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn^2+, which element is oxidized? (2020)
A.
Ag
B.
Zn
C.
O
D.
None of the above
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Solution
In this reaction, zinc (Zn) is oxidized as it loses electrons to form Zn^2+.
Correct Answer: B — Zn
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Q. In the reaction 2Ag⁺ + Zn → 2Ag + Zn²⁺, which species is reduced? (2023)
A.
Ag⁺
B.
Zn
C.
Ag
D.
Zn²⁺
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Solution
In this reaction, Ag⁺ gains electrons to form Ag, thus it is reduced.
Correct Answer: A — Ag⁺
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, which element is oxidized?
A.
Fe
B.
Cl2
C.
FeCl3
D.
None of the above
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Solution
Iron (Fe) is oxidized as it loses electrons to form FeCl3.
Correct Answer: A — Fe
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being reduced? (2020) 2020
A.
Fe2O3
B.
C
C.
CO2
D.
Fe
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Solution
Fe2O3 is reduced to Fe, as it gains electrons during the reaction.
Correct Answer: A — Fe2O3
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, which species is oxidized? (2019)
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
In this reaction, carbon (C) is oxidized as it loses electrons to form CO2.
Correct Answer: B — C
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Q. In the reaction 2Fe²⁺ + 2e⁻ → 2Fe, what is being reduced? (2021)
A.
Fe²⁺
B.
Fe
C.
e⁻
D.
None of the above
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Solution
In this reaction, Fe²⁺ is being reduced as it gains electrons to form Fe.
Correct Answer: A — Fe²⁺
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Q. In the reaction 2Fe²⁺ + 2MnO4⁻ → 2Fe³⁺ + 2Mn²⁺, what is the oxidation state change for iron? (2021)
A.
+2 to +3
B.
+3 to +2
C.
0 to +2
D.
−2 to 0
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Solution
Iron changes its oxidation state from +2 to +3, indicating that it is oxidized.
Correct Answer: A — +2 to +3
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Q. In the reaction 2Fe²⁺ + Cl2 → 2Fe³⁺ + 2Cl⁻, what is being oxidized? (2021)
A.
Fe²⁺
B.
Cl2
C.
Fe³⁺
D.
Cl⁻
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Solution
In this reaction, Fe²⁺ is being oxidized to Fe³⁺ as it loses electrons.
Correct Answer: A — Fe²⁺
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Q. In the reaction 2Mg + O2 → 2MgO, which element is oxidized? (2021)
A.
Magnesium
B.
Oxygen
C.
Both Magnesium and Oxygen
D.
Neither Magnesium nor Oxygen
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Solution
Magnesium is oxidized as it loses electrons and its oxidation state increases from 0 to +2.
Correct Answer: A — Magnesium
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Q. In the reaction 2MnO4- + 5C2O4^2- + 16H+ → 2Mn^2+ + 10CO2 + 8H2O, what is being oxidized? (2019)
A.
MnO4-
B.
C2O4^2-
C.
H+
D.
CO2
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Solution
C2O4^2- (oxalate ion) is being oxidized to CO2 in this reaction.
Correct Answer: B — C2O4^2-
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if the volume of the container is increased? (2023)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
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Solution
According to Le Chatelier's principle, increasing the volume of the container decreases the pressure. The equilibrium will shift towards the side with more moles of gas, which is the left side (2 moles of SO2 + 1 mole of O2).
Correct Answer: B — Shift to the left
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Q. In the reaction 3H2 + N2 → 2NH3, which element is reduced? (2022)
A.
H2
B.
N2
C.
NH3
D.
None
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Solution
N2 is reduced to NH3 as it gains electrons.
Correct Answer: B — N2
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, which element is oxidized?
A.
Fe
B.
O2
C.
Fe2O3
D.
None of the above
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Solution
Iron (Fe) is oxidized as it loses electrons to form Fe2O3.
Correct Answer: A — Fe
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Q. In the reaction A(g) + B(g) ⇌ C(g) + D(g), if the temperature is increased, what will be the effect on the equilibrium if the reaction is exothermic? (2020)
A.
The equilibrium shifts to the left
B.
The equilibrium shifts to the right
C.
No effect on the equilibrium
D.
The reaction rate increases
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left (towards the reactants) to absorb the added heat, according to Le Chatelier's principle.
Correct Answer: A — The equilibrium shifts to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), if H2 is removed from the system, what will happen to the equilibrium? (2022)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
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Solution
Removing H2 will shift the equilibrium to the left to produce more H2, according to Le Chatelier's principle.
Correct Answer: B — Shift to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what effect does increasing the temperature have if the reaction is exothermic? (2020)
A.
Shifts equilibrium to the right
B.
Shifts equilibrium to the left
C.
No effect on equilibrium
D.
Increases the rate of reaction
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants, as the system tries to absorb the added heat.
Correct Answer: B — Shifts equilibrium to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what is the effect of increasing the concentration of CO? (2023)
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in Kp
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Solution
Increasing the concentration of CO will shift the equilibrium to the right, favoring the formation of CH3OH.
Correct Answer: A — Shift to the right
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Q. In the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens to the equilibrium position if the pressure is increased? (2023)
A.
Shifts to the left
B.
Shifts to the right
C.
No change
D.
Depends on temperature
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Solution
Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas, which in this case is the right side (2 moles of NH3).
Correct Answer: B — Shifts to the right
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Q. In the reaction Zn + CuSO4 → ZnSO4 + Cu, which species is reduced?
A.
Zn
B.
CuSO4
C.
ZnSO4
D.
Cu
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Solution
Copper (Cu) is reduced as it gains electrons from zinc.
Correct Answer: D — Cu
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Q. In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, which element is oxidized? (2022)
A.
Zn
B.
Cu²⁺
C.
Zn²⁺
D.
Cu
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Solution
Zinc (Zn) is oxidized as it loses electrons to form Zn²⁺.
Correct Answer: A — Zn
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Q. In the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g), what effect does increasing the pressure have? (2020)
A.
Shifts equilibrium to the left
B.
Shifts equilibrium to the right
C.
No effect on equilibrium
D.
Increases the rate of reaction
Show solution
Solution
Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas. In this case, it shifts to the right, producing more SO3.
Correct Answer: B — Shifts equilibrium to the right
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Q. In the redox reaction 2Ag+ + Cu → 2Ag + Cu2+, which species is oxidized? (2022) 2022
A.
Ag+
B.
Cu
C.
Ag
D.
Cu2+
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Solution
Cu is oxidized to Cu2+ as it loses electrons in the reaction.
Correct Answer: B — Cu
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Q. In the redox reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is oxidized? (2021)
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Zn is oxidized to Zn2+ as it loses electrons.
Correct Answer: B — Zn
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Q. In the redox reaction 2MnO4- + 5C2O4^2- + 16H+ → 2Mn^2+ + 10CO2 + 8H2O, what is the oxidation state of carbon in C2O4^2-?
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Solution
In C2O4^2-, the oxidation state of carbon is +3.
Correct Answer: C — +4
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Q. In thermodynamics, the term 'system' refers to: (2022)
A.
The surroundings
B.
The part of the universe under study
C.
The entire universe
D.
None of the above
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Solution
In thermodynamics, the 'system' refers to the part of the universe that is being studied, while the surroundings are everything else.
Correct Answer: B — The part of the universe under study
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Q. In thermodynamics, what does the term 'enthalpy' (H) represent? (2020)
A.
Total energy of the system
B.
Energy required to break bonds
C.
Heat content of the system at constant pressure
D.
Work done by the system
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Solution
Enthalpy (H) represents the heat content of the system at constant pressure, defined as H = U + PV.
Correct Answer: C — Heat content of the system at constant pressure
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Q. In thin film interference, which of the following will cause a shift in the interference pattern? (2022)
A.
Change in wavelength
B.
Change in film thickness
C.
Change in angle of incidence
D.
All of the above
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Solution
All these factors can affect the path difference and thus shift the interference pattern in thin film interference.
Correct Answer: D — All of the above
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Q. In which case does total internal reflection occur? (2022)
A.
When light travels from a denser to a rarer medium
B.
When light travels from a rarer to a denser medium
C.
At the critical angle
D.
None of the above
Show solution
Solution
Total internal reflection occurs when light travels from a denser medium to a rarer medium at an angle greater than the critical angle.
Correct Answer: A — When light travels from a denser to a rarer medium
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