1. What does 'Redox' in redox reactions stand for?
Answer:
Explanation:
The term 'Redox' is derived from the words "Reduction" and "Oxidation".
2. In a redox reaction, the substance that is reduced:
Answer:
Explanation:
Reduction is defined as the gain of electrons.
3. Which of the following is an oxidizing agent?
Answer:
Explanation:
An oxidizing agent accepts electrons. O2 readily accepts electrons, making it an oxidizing agent.
4. Oxidation number of oxygen in most compounds is:
Answer:
Explanation:
Oxygen usually has an oxidation number of -2, except in peroxides and some specific compounds.
5. Which of the following reactions is NOT a redox reaction?
Answer:
Explanation:
This is a neutralization reaction where there is no transfer of electrons.
6. The oxidation number of sulfur in H2SO4 is:
Answer:
Explanation:
By assigning oxidation numbers to the atoms in the compound, we find sulfur to have an oxidation state of +6 in H2SO4.
7. Which substance acts as a reducing agent in the following reaction?
Answer:
Explanation:
H2 donates electrons (gets oxidized) to O2. Hence, H2 acts as a reducing agent.
8. In which of the following is the oxidation number of nitrogen zero?
Answer:
Explanation:
In N2, nitrogen is in its elemental form and thus has an oxidation number of zero.
9. An increase in oxidation number indicates:
Answer:
Explanation:
An increase in oxidation number corresponds to a loss of electrons, which indicates oxidation.
10. Which element is undergoing reduction in the reaction:
Answer:
Explanation:
Cu in CuSO4 gains electrons from Zn and is reduced to elemental Cu.
11. Oxidation is always accompanied by:
Answer:
Explanation:
In redox reactions, if one substance is oxidized, another must be reduced. Hence, oxidation is always accompanied by reduction.
12. The substance that loses electrons is called:
Answer:
Explanation:
The substance that loses electrons (gets oxidized) is called a reducing agent.
13. In the reaction: 2K + Cl2 -> 2KCl, what is the oxidizing agent?
Answer:
Explanation:
Cl2 gains electrons from K and hence acts as an oxidizing agent.
14. The oxidation number of hydrogen in most of its compounds is:
Answer:
Explanation:
In most of its compounds, hydrogen has an oxidation number of +1.
15. In which of the following compounds is the oxidation number of carbon +4?
Answer:
Explanation:
In methane (CH4), carbon has an oxidation number of +4.
16. A reaction in which both oxidation and reduction occur is termed as:
Answer:
Explanation:
Redox reactions involve both oxidation and reduction processes.
17. In a disproportionation reaction, a substance:
Answer:
Explanation:
In a disproportionation reaction, the same substance undergoes both oxidation and reduction.
18. Which of the following elements has the highest ability to act as an oxidizing agent?
Answer:
Explanation:
Chlorine (Cl) has a higher tendency to accept electrons, making it a strong oxidizing agent.
19. The oxidation number of chromium in K2Cr2O7 is:
Answer:
Explanation:
By assigning oxidation numbers to the atoms, we find chromium to have an oxidation state of +6 in K2Cr2O7.
20. In which of the following reactions is hydrogen acting as an oxidizing agent?
Answer:
Explanation:
In all the reactions provided, hydrogen is being reduced, hence it cannot act as an oxidizing agent.