AP Chemistry · Topic 4.9
Oxidation-Reduction Reactions Practice
Part of Chemical Reactions.(TRA-2.C)
Practice questions
22
Sample questions
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Sample 1difficulty 1/5
Oxidation is
- A
Loss of mass
- B
Gain of electrons
- Ccheck_circle
Loss of electrons
- D
Gain of protons
Why
OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).
- A
Sample 2difficulty 1/5
The oxidation state of any element in its standard form (e.g., O₂, H₂, Fe, Na) is
- A
−1
- B
Variable
- C
+1
- Dcheck_circle
0
Why
Pure elements always have ox. state 0. Charge of monatomic ion = ox. state.
- A
Sample 3difficulty 2/5
Oxidation is _______; reduction is _______.
- A
gain of electrons; loss of electrons
- Bcheck_circle
loss of electrons; gain of electrons
- C
addition of oxygen; loss of hydrogen
- D
neither
Why
"OIL RIG" mnemonic. Oxidation Is Loss; Reduction Is Gain (of electrons). Oxidation state increases when oxidized.
- A
Sample 4difficulty 2/5
The oxidation state of N in NH₄⁺ is
- A
+3
- B
0
- C
+1
- Dcheck_circle
−3
Why
H is +1 each. Sum: N + 4(+1) = +1 → N = -3.
- A
Sample 5difficulty 2/5
Oxidation number of S in SO₄²⁻ is
- A
+4
- Bcheck_circle
+6
- C
−2
- D
+2
Why
O is −2 each (×4 = −8); total charge is −2 → S = +6.
- A