Q. In the expansion of (x - 1)^5, what is the coefficient of x^3?
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Solution
The coefficient of x^3 is C(5,3) * (-1)^2 = 10.
Correct Answer: A — -10
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Q. In the hydrogen atom, which transition would emit the photon with the highest energy? (2019)
A.
n=2 to n=1
B.
n=3 to n=2
C.
n=4 to n=3
D.
n=5 to n=4
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Solution
The energy of the emitted photon is highest for the transition from n=2 to n=1, as it involves the largest energy difference.
Correct Answer: A — n=2 to n=1
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Q. In the kinetic theory of gases, the temperature of a gas is a measure of: (2022)
A.
The average potential energy of the molecules
B.
The average kinetic energy of the molecules
C.
The total energy of the gas
D.
The number of molecules in the gas
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Solution
In the kinetic theory of gases, the temperature of a gas is a measure of the average kinetic energy of the molecules.
Correct Answer: B — The average kinetic energy of the molecules
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Q. In the kinetic theory of gases, the term 'elastic collision' means: (2019)
A.
Kinetic energy is conserved
B.
Momentum is conserved
C.
Both kinetic energy and momentum are conserved
D.
Neither kinetic energy nor momentum is conserved
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Solution
In elastic collisions, both kinetic energy and momentum are conserved, which is a key assumption in the kinetic theory of gases.
Correct Answer: C — Both kinetic energy and momentum are conserved
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Q. In the kinetic theory, the internal energy of an ideal gas is primarily due to:
A.
Potential energy
B.
Kinetic energy of molecules
C.
Work done on the gas
D.
Heat energy
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Solution
In an ideal gas, the internal energy is primarily due to the kinetic energy of the gas molecules, as potential energy is negligible.
Correct Answer: B — Kinetic energy of molecules
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Q. In the kinetic theory, the temperature of a gas is a measure of: (2022)
A.
The average potential energy of the molecules
B.
The average kinetic energy of the molecules
C.
The total energy of the gas
D.
The speed of the gas molecules
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Solution
In the kinetic theory, the temperature of a gas is a measure of the average kinetic energy of the molecules.
Correct Answer: B — The average kinetic energy of the molecules
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Q. In the Langmuir adsorption isotherm, which assumption is NOT made? (2019)
A.
Adsorption occurs on a surface with a finite number of identical sites
B.
Adsorption is reversible
C.
There is no interaction between adsorbed molecules
D.
Adsorption occurs only at high pressures
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Solution
The Langmuir isotherm assumes that adsorption occurs at all pressures, not just high pressures.
Correct Answer: D — Adsorption occurs only at high pressures
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Q. In the photoelectric effect, if the frequency of incident light is doubled, what happens to the kinetic energy of emitted electrons? (2020)
A.
It doubles
B.
It quadruples
C.
It remains the same
D.
It becomes zero
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Solution
Kinetic energy (KE) = hf - φ. If frequency is doubled, KE increases by a factor of 4.
Correct Answer: B — It quadruples
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Q. In the photoelectric effect, what happens to the kinetic energy of emitted electrons when the frequency of incident light is increased? (2021)
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
According to the photoelectric effect, the kinetic energy of emitted electrons increases with the frequency of the incident light, provided the frequency is above the threshold frequency.
Correct Answer: A — Increases
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Q. In the photoelectric effect, what happens to the kinetic energy of emitted electrons as the frequency of incident light increases? (2021)
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
According to the photoelectric effect, the kinetic energy of emitted electrons increases with the frequency of the incident light, provided the frequency is above the threshold frequency.
Correct Answer: A — Increases
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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 2MnO4⁻ + 5C2O4²⁻ + 16H⁺ → 2Mn²⁺ + 10CO2 + 8H2O, which species is reduced? (2019)
A.
MnO4⁻
B.
C2O4²⁻
C.
H⁺
D.
CO2
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Solution
In this reaction, MnO4⁻ is reduced to Mn²⁺ as it gains electrons.
Correct Answer: A — MnO4⁻
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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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