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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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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of water are produced from 4 moles of hydrogen?
A.
2 moles
B.
4 moles
C.
6 moles
D.
8 moles
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Solution
According to the stoichiometry of the reaction, 2 moles of H2 produce 2 moles of H2O. Therefore, 4 moles of H2 will produce 4 moles of H2O.
Correct Answer: B — 4 moles
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Q. In the reaction 2H2 + O2 → 2H2O, if 3 moles of O2 are available, how many moles of H2 are required?
A.
3 moles
B.
6 moles
C.
1.5 moles
D.
4.5 moles
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Solution
According to the stoichiometry, 1 mole of O2 requires 2 moles of H2. Therefore, 3 moles of O2 will require 3 x 2 = 6 moles of H2.
Correct Answer: B — 6 moles
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Q. In the reaction 2H2 + O2 → 2H2O, what is the ratio of moles of hydrogen to moles of oxygen?
A.
1:1
B.
2:1
C.
2:2
D.
1:2
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Solution
The balanced equation shows that 2 moles of H2 react with 1 mole of O2, giving a ratio of 2:1.
Correct Answer: B — 2:1
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Q. In the reaction 2H2 + O2 → 2H2O, which element is oxidized?
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Solution
Oxygen (O) is oxidized as it goes from 0 in O2 to -2 in H2O.
Correct Answer: B — O
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Q. In the reaction 2Na + Cl2 → 2NaCl, how many grams of NaCl can be produced from 5 g of Na?
A.
10 g
B.
15 g
C.
20 g
D.
25 g
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Solution
5 g of Na = 0.217 moles. 2 moles of Na produce 2 moles of NaCl, so 0.217 moles of NaCl = 0.217 * 58.5 g = 12.7 g.
Correct Answer: A — 10 g
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens if SO2 is removed from the system?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
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Solution
Removing SO2 will shift the equilibrium to the left to produce more SO2, according to Le Chatelier's principle.
Correct Answer: B — Shift to the left
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