Question 61:
In the reaction Zn+Cu2+→Zn2++CuZn+Cu2+→Zn2++Cu, which species is oxidized?
A) ZnZn
B) Cu2+Cu2+
C) CuCu
D) Zn2+Zn2+
Answer: A) ZnZn
Explanation: Zinc is oxidized as it loses electrons to become Zn2+Zn2+.
Question 62:
Which of the following species is oxidized in the reaction 2MnO4−+5C2O42−+6H+→2Mn2++10CO2+3H2O2MnO4−+5C2O42−+6H+→2Mn2++10CO2+3H2O?
A) C2O42−C2O42−
B) MnO4−MnO4−
C) H+H+
D) CO2CO2
Answer: A) C2O42−C2O42−
Explanation: The oxalate ion C2O42−C2O42− is oxidized to CO2CO2.
Question 63:
In the electrochemical series, which of the following metals is the best reducing agent?
A) AuAu
B) AgAg
C) LiLi
D) CuCu
Answer: C) LiLi
Explanation: Lithium is a strong reducing agent because it has a high tendency to lose electrons.
Question 64:
What is the oxidation state of chromium in CrO42−CrO42−?
A) +2
B) +3
C) +4
D) +6
Answer: D) +6
Explanation: In the chromate ion CrO42−CrO42−, chromium has an oxidation state of +6.
Question 65:
Which of the following represents a reduction reaction?
A) Na→Na++e−Na→Na++e−
B) Cl+e−→Cl−Cl+e−→Cl−
C) Fe3+→FeFe3+→Fe
D) Both B and C
Answer: D) Both B and C
Explanation: Both reactions show a gain of electrons, indicating reduction.
Question 66:
Which of the following ions is most likely to undergo reduction?
A) Ca2+Ca2+
B) Mg2+Mg2+
C) Ag+Ag+
D) K+K+
Answer: C) Ag+Ag+
Explanation: Silver ion Ag+Ag+ can easily gain an electron to become elemental silver, indicating it is likely to undergo reduction.
Question 67:
What happens to the oxidation state of an element during oxidation?
A) It decreases.
B) It increases.
C) It remains the same.
D) It becomes negative.
Answer: B) It increases.
Explanation: During oxidation, an element loses electrons, resulting in an increase in its oxidation state.
Question 68:
In the reaction 2Na+Cl2→2NaCl2Na+Cl2→2NaCl, what is the oxidation state of sodium in NaClNaCl?
A) +1
B) 0
C) -1
D) +2
Answer: A) +1
Explanation: In sodium chloride (NaClNaCl), sodium has an oxidation state of +1.
Question 69:
In which of the following reactions is sulfur both oxidized and reduced?
A) 2S+3O2→2SO32S+3O2→2SO3
B) 2H2S→2S+2H22H2S→2S+2H2
C) 2SO2+O2→2SO32SO2+O2→2SO3
D) 4H2+S→2H2S4H2+S→2H2S
Answer: B) 2H2S→2S+2H22H2S→2S+2H2
Explanation: In this reaction, sulfur in hydrogen sulfide is oxidized to elemental sulfur and also reduced in the process of formation of hydrogen.
Question 70:
What is the oxidation state of nitrogen in NH4+NH4+?
A) -3
B) +3
C) +1
D) 0
Answer: A) -3
Explanation: In ammonium ion (NH4+NH4+), nitrogen has an oxidation state of -3.
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