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Q. In the photoelectric effect, what does the term 'work function' refer to?
A.
The energy of the incident photons
B.
The energy required to remove an electron from the metal
C.
The maximum kinetic energy of emitted electrons
D.
The frequency of the incident light
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Solution
The work function is the minimum energy required to remove an electron from the surface of a metal.
Correct Answer: B — The energy required to remove an electron from the metal
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Q. In the photoelectric effect, what does the work function represent?
A.
The energy of the incident photons
B.
The maximum kinetic energy of emitted electrons
C.
The minimum energy required to remove an electron from the metal
D.
The frequency of the incident light
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Solution
The work function is the minimum energy required to remove an electron from the surface of the metal.
Correct Answer: C — The minimum energy required to remove an electron from the metal
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Q. In the photoelectric effect, what happens to the emitted electrons if the frequency of the incident light is just at the threshold frequency?
A.
They are emitted with maximum kinetic energy
B.
They are emitted with zero kinetic energy
C.
They are not emitted
D.
They are emitted with negative kinetic energy
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Solution
At the threshold frequency, the energy of the incident photons is equal to the work function, resulting in emitted electrons having zero kinetic energy.
Correct Answer: B — They are emitted with zero kinetic energy
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Q. In the photoelectric effect, what happens to the energy of the incident photon if it exceeds the work function?
A.
All energy is used to emit electrons
B.
Excess energy becomes kinetic energy
C.
No electrons are emitted
D.
Energy is lost as heat
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Solution
The excess energy of the photon becomes the kinetic energy of the emitted photoelectrons.
Correct Answer: B — Excess energy becomes kinetic energy
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Q. In the photoelectric effect, what happens to the kinetic energy of emitted electrons if the frequency of incident light is increased?
A.
It decreases
B.
It remains constant
C.
It increases linearly with frequency
D.
It increases with the square of frequency
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Solution
The kinetic energy of emitted electrons increases linearly with the frequency of the incident light, according to the equation KE = hf - φ.
Correct Answer: C — It increases linearly with frequency
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Q. In the photoelectric effect, what happens to the kinetic energy of emitted electrons if the intensity of light is increased while keeping frequency constant?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
The kinetic energy of emitted electrons remains the same as it depends on the frequency, not intensity.
Correct Answer: C — Remains the same
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Q. In the photoelectric effect, what happens to the kinetic energy of the emitted electrons if the frequency of the incident light is increased?
A.
It decreases
B.
It remains constant
C.
It increases
D.
It becomes negative
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Solution
The kinetic energy of the emitted electrons increases with the frequency of the incident light, as given by the equation KE = hf - φ, where φ is the work function.
Correct Answer: C — It increases
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Q. In the photoelectric effect, what is the effect of increasing the frequency of incident light beyond the threshold frequency?
A.
No effect on the emitted electrons
B.
Increases the number of emitted electrons
C.
Increases the kinetic energy of emitted electrons
D.
Decreases the work function
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Solution
Increasing the frequency beyond the threshold increases the kinetic energy of the emitted electrons, as per the equation KE = hf - φ.
Correct Answer: C — Increases the kinetic energy of emitted electrons
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Q. In the photoelectric effect, what is the effect of increasing the wavelength of incident light?
A.
Increases the kinetic energy of emitted electrons
B.
Decreases the kinetic energy of emitted electrons
C.
Has no effect on the photoelectric effect
D.
Increases the number of emitted electrons
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Solution
Increasing the wavelength decreases the frequency of the light, which reduces the energy of the incident photons, thus decreasing the kinetic energy of emitted electrons.
Correct Answer: B — Decreases the kinetic energy of emitted electrons
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Q. In the photoelectric effect, which of the following factors does NOT affect the photoelectric current?
A.
Intensity of light
B.
Frequency of light
C.
Surface area of the metal
D.
Type of metal
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Solution
The frequency of light must be above a certain threshold to emit electrons, but once that is achieved, the photoelectric current depends on the intensity, not the frequency.
Correct Answer: B — Frequency of light
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is oxidized?
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Zinc (Zn) is oxidized to Zn2+.
Correct Answer: B — Zn
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is reduced?
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Ag+ is reduced as it gains electrons to form Ag.
Correct Answer: A — Ag+
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Q. In the reaction 2AgNO3 + Cu → 2Ag + Cu(NO3)2, what is the oxidation state of silver in AgNO3?
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Solution
In AgNO3, silver has an oxidation state of +1.
Correct Answer: A — +1
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Q. In the reaction 2Ag^+ + Zn → 2Ag + Zn^2+, what is the oxidation state change for zinc?
A.
0 to +2
B.
+2 to 0
C.
+2 to +1
D.
0 to -1
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Solution
Zinc is oxidized from an oxidation state of 0 to +2.
Correct Answer: A — 0 to +2
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Q. In the reaction 2Cr2O7^2- + 14H+ + 6e^- → 4Cr^3+ + 7H2O, what is the role of Cr2O7^2-?
A.
Oxidizing agent
B.
Reducing agent
C.
Neutral agent
D.
None of the above
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Solution
Cr2O7^2- is reduced to Cr^3+, making it the oxidizing agent.
Correct Answer: A — Oxidizing agent
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many grams of FeCl3 can be produced from 4 moles of Fe?
A.
315.5 g
B.
267 g
C.
200 g
D.
150 g
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Solution
4 moles of Fe produce 4 moles of FeCl3. Mass of FeCl3 = 4 moles * 162.5 g/mole = 650 g.
Correct Answer: A — 315.5 g
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many grams of FeCl3 can be produced from 10 g of Fe?
A.
20 g
B.
30 g
C.
40 g
D.
50 g
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Solution
10 g of Fe = 0.18 moles. 2 moles of Fe produce 2 moles of FeCl3. 0.18 moles of FeCl3 = 0.18 * 162.5 g = 29.25 g.
Correct Answer: C — 40 g
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many grams of FeCl3 can be produced from 4 grams of Fe?
A.
12 g
B.
20 g
C.
30 g
D.
40 g
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Solution
4 g of Fe = 0.071 moles. 0.071 moles of Fe produce 0.071 * 2 = 0.142 moles of FeCl3 = 0.142 * 162.5 g = 23 g.
Correct Answer: B — 20 g
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many moles of Cl2 are needed to react with 4 moles of Fe?
A.
3 moles
B.
6 moles
C.
4 moles
D.
2 moles
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Solution
According to the stoichiometry, 2 moles of Fe require 3 moles of Cl2. Therefore, 4 moles of Fe will require 6 moles of Cl2.
Correct Answer: B — 6 moles
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being oxidized?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
Carbon (C) is being oxidized to carbon dioxide (CO2).
Correct Answer: B — C
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being reduced?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
Fe2O3 is being reduced to Fe as it gains electrons.
Correct Answer: A — Fe2O3
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, which element is oxidized?
A.
Iron
B.
Carbon
C.
Oxygen
D.
None
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Solution
Carbon is oxidized as it loses electrons to form CO2.
Correct Answer: B — Carbon
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Q. In the reaction 2Fe^3+ + 2I^- → 2Fe^2+ + I2, which species is the reducing agent?
A.
Fe^3+
B.
I^-
C.
Fe^2+
D.
I2
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Solution
I^- donates electrons to Fe^3+, thus it is the reducing agent.
Correct Answer: B — I^-
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of oxygen are required to completely react with 4 grams of hydrogen?
A.
16 g
B.
8 g
C.
32 g
D.
4 g
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Solution
4 g of H2 = 2 moles. 1 mole of O2 is needed for 2 moles of H2, so 1 mole of O2 = 32 g is required.
Correct Answer: B — 8 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of oxygen are required to react with 4 grams of hydrogen?
A.
16 g
B.
8 g
C.
4 g
D.
2 g
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Solution
First, calculate moles of H2: 4 g / 2 g/mol = 2 moles. From the reaction, 2 moles of H2 require 1 mole of O2. Therefore, 2 moles of O2 = 32 g.
Correct Answer: B — 8 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of water are produced from 4 grams of hydrogen?
A.
18 g
B.
36 g
C.
54 g
D.
72 g
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Solution
4 grams of H2 is 2 moles (4 g / 2 g/mol). According to the equation, 2 moles of H2 produce 2 moles of H2O, which is 36 g (2 moles x 18 g/mol).
Correct Answer: B — 36 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of water can be produced from 4 grams of hydrogen?
A.
36 g
B.
18 g
C.
72 g
D.
9 g
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Solution
4 g of H2 = 2 moles. 2 moles of H2 produce 2 moles of H2O = 2 * 18 g = 36 g.
Correct Answer: A — 36 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many liters of H2O vapor are produced from 4 liters of H2?
A.
4 L
B.
8 L
C.
2 L
D.
6 L
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Solution
4 L of H2 produces 4 L of H2O vapor at STP.
Correct Answer: B — 8 L
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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of O2 are required to completely react with 6 moles of H2?
A.
2 moles
B.
3 moles
C.
4 moles
D.
6 moles
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Solution
From the balanced equation, 2 moles of H2 require 1 mole of O2. Therefore, 6 moles of H2 will require (6/2) = 3 moles of O2.
Correct Answer: B — 3 moles
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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of O2 are required to react with 6 moles of H2?
A.
3 moles
B.
4 moles
C.
6 moles
D.
2 moles
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Solution
According to the stoichiometry of the reaction, 2 moles of H2 require 1 mole of O2. Therefore, 6 moles of H2 will require (6/2) = 3 moles of O2.
Correct Answer: A — 3 moles
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