Q.1 Which of the following species gets reduced in the reaction: 2Fe2O3 + 3C → 4Fe + 3CO2?
Fe2O3
C
CO2
Fe
Explanation - Fe in Fe2O3 has an oxidation state of +3 and is reduced to 0 in Fe metal.
Correct answer is: Fe2O3
Q.2 In the reaction Zn + CuSO4 → ZnSO4 + Cu, which is the oxidizing agent?
Zn
Cu
CuSO4
ZnSO4
Explanation - Cu^2+ in CuSO4 gains electrons and is reduced, hence CuSO4 acts as the oxidizing agent.
Correct answer is: CuSO4
Q.3 Which of the following is a redox reaction?
HCl + NaOH → NaCl + H2O
Zn + HCl → ZnCl2 + H2
BaCl2 + Na2SO4 → BaSO4 + 2NaCl
AgNO3 + NaCl → AgCl + NaNO3
Explanation - Zn is oxidized from 0 to +2 and H^+ is reduced from +1 to 0 in H2, so it is a redox reaction.
Correct answer is: Zn + HCl → ZnCl2 + H2
Q.4 What is the oxidation number of Mn in KMnO4?
+2
+4
+6
+7
Explanation - K is +1, O is -2. Let Mn be x: 1 + x + 4(-2) = 0 → x = +7.
Correct answer is: +7
Q.5 In which of the following reactions does chlorine act as an oxidizing agent?
Cl2 + 2KBr → 2KCl + Br2
Cl2 + 2Na → 2NaCl
Cl2 + H2 → 2HCl
All of the above
Explanation - Cl2 gains electrons from Br^- to form Cl^-, thus acting as an oxidizing agent.
Correct answer is: Cl2 + 2KBr → 2KCl + Br2
Q.6 Which of the following metals cannot reduce water at room temperature?
Na
Mg
Zn
Cu
Explanation - Copper is less reactive and cannot displace hydrogen from water at room temperature.
Correct answer is: Cu
Q.7 In the reaction H2O2 → H2O + O2, the substance acting as both oxidizing and reducing agent is:
H2O
O2
H2O2
None
Explanation - H2O2 is oxidized to O2 and reduced to H2O, so it acts as both oxidizing and reducing agent (disproportionation).
Correct answer is: H2O2
Q.8 Which of the following represents a disproportionation reaction?
Cl2 + 2NaOH → NaCl + NaClO + H2O
Zn + 2HCl → ZnCl2 + H2
Fe2O3 + 3CO → 2Fe + 3CO2
2K + Br2 → 2KBr
Explanation - Chlorine is simultaneously reduced to Cl^- and oxidized to ClO^-.
Correct answer is: Cl2 + 2NaOH → NaCl + NaClO + H2O
Q.9 Which of the following elements shows the maximum oxidation number in its compounds?
Oxygen
Chlorine
Sulfur
Nitrogen
Explanation - Chlorine can exhibit +7 in compounds like HClO4, which is higher than S (+6) and N (+5).
Correct answer is: Chlorine
Q.10 In the reaction Fe2(SO4)3 + 2Na → 2Fe + Na2SO4, which element is oxidized?
Fe
Na
S
O
Explanation - Na goes from 0 to +1, hence Na is oxidized.
Correct answer is: Na
Q.11 Which of the following can act as both an oxidizing and reducing agent?
Cl2
H2O2
KMnO4
NaCl
Explanation - Hydrogen peroxide undergoes disproportionation, being oxidized and reduced simultaneously.
Correct answer is: H2O2
Q.12 In the reaction 2Cr + 3Cl2 → 2CrCl3, chromium is:
Oxidized
Reduced
Both oxidized and reduced
Neither
Explanation - Chromium goes from 0 in Cr to +3 in CrCl3, hence it is oxidized.
Correct answer is: Oxidized
Q.13 Which of the following halogens is the strongest oxidizing agent in aqueous solution?
F2
Cl2
Br2
I2
Explanation - Fluorine is the most electronegative and can easily accept electrons, making it the strongest oxidizing agent.
Correct answer is: F2
Q.14 In the reaction 2AgNO3 + Cu → Cu(NO3)2 + 2Ag, the reducing agent is:
AgNO3
Cu
Cu(NO3)2
Ag
Explanation - Cu is oxidized from 0 to +2, so it acts as the reducing agent.
Correct answer is: Cu
Q.15 Which of the following statements is true for redox reactions?
Oxidation and reduction occur separately
Oxidation involves gain of electrons
Reduction involves loss of electrons
Oxidation and reduction occur simultaneously
Explanation - In redox reactions, the substance oxidized loses electrons while the substance reduced gains electrons at the same time.
Correct answer is: Oxidation and reduction occur simultaneously
Q.16 In acidic medium, the MnO4^- ion is reduced to:
MnO2
Mn^2+
Mn
Mn2O3
Explanation - In acidic medium, permanganate ion (Mn +7) is reduced to Mn^2+ (oxidation state +2).
Correct answer is: Mn^2+
Q.17 Which element has the highest tendency to get oxidized?
K
Mg
Al
Fe
Explanation - Potassium is highly reactive and easily loses an electron, so it is most easily oxidized.
Correct answer is: K
Q.18 In the reaction 2H2 + O2 → 2H2O, which element is reduced?
H
O
Both H and O
Neither
Explanation - Oxygen goes from 0 to -2 in H2O, hence oxygen is reduced.
Correct answer is: O
Q.19 Which of the following is a non-redox reaction?
HCl + NaOH → NaCl + H2O
Zn + HCl → ZnCl2 + H2
Fe + CuSO4 → FeSO4 + Cu
2K + Br2 → 2KBr
Explanation - No change in oxidation states occurs; it is an acid-base neutralization, not a redox reaction.
Correct answer is: HCl + NaOH → NaCl + H2O
Q.20 In the reaction Cl2 + 2KI → 2KCl + I2, iodine is:
Oxidized
Reduced
Both oxidized and reduced
Neither
Explanation - I^- goes from -1 in KI to 0 in I2, so iodine is oxidized.
Correct answer is: Oxidized
Q.21 The oxidation number of sulfur in H2SO4 is:
+4
+6
+2
+1
Explanation - Let oxidation number of S be x: 2(+1) + x + 4(-2) = 0 → x = +6.
Correct answer is: +6
Q.22 In basic medium, the MnO4^- ion is reduced to:
MnO2
Mn^2+
Mn
Mn2O3
Explanation - In basic medium, permanganate ion (Mn +7) is reduced to MnO2 (Mn +4).
Correct answer is: MnO2
Q.23 Which of the following halogens can displace another halogen from its salt?
F2 can displace Cl^- from NaCl
Cl2 can displace Br^- from KBr
Br2 can displace I^- from KI
All of the above
Explanation - More electronegative halogens can displace less electronegative halogens from their salts.
Correct answer is: All of the above
Q.24 In the reaction Cu + 2AgNO3 → Cu(NO3)2 + 2Ag, the oxidizing agent is:
Cu
Ag
AgNO3
Cu(NO3)2
Explanation - Ag^+ is reduced to Ag, thus AgNO3 acts as the oxidizing agent.
Correct answer is: AgNO3