Question 1

Which of the following statements best describes oxidation in a redox reaction?

Accepted Answer

Oxidation is the loss of electrons by an atom or ion.

Question 2

In the reaction $$ \mathrm{Zn} + 2\mathrm{HCl} \rightarrow \mathrm{ZnCl}_2 + \mathrm{H}_2 $$, which species is oxidized?

Accepted Answer

$$\mathrm{Zn}$$

Question 3

What is the oxidation number of sulfur in $$\mathrm{SO}_4$$^{2-}$$?

Accepted Answer

$$+6$$

Question 4

Which of the following is always true for the oxidation number of an element in its elemental form?

Accepted Answer

It is zero.

Question 5

In the nickel–cadmium battery, the oxidation state of Cd changes from 0 to $$+2. $$What role does Cd play in this reaction?

Accepted Answer

Cd is the reducing agent.

Question 6

Which of the following best describes the function of an oxidizing agent in a redox reaction?

Accepted Answer

It gains electrons and is reduced.

Question 7

A student mixes zinc metal with hydrochloric acid and observes a temperature increase. What type of reaction is this?

Accepted Answer

Exothermic, because heat is released.

Question 8

Which of the following is the correct sum of oxidation numbers for all atoms in a neutral compound?

Accepted Answer

It is always zero.

Question 9

Consider the reaction: $$\mathrm{Fe}^{2+} + \mathrm{Cl}_2 \rightarrow \mathrm{Fe}^{3+} + 2\mathrm{Cl}^-. $$Which species is reduced?

Accepted Answer

$$\mathrm{Cl}_2$$

Question 10

A polyatomic ion has a charge of $$-1. $$What must be true about the sum of the oxidation numbers of all atoms in the ion?

Accepted Answer

The sum is $$-1.$$

Question 11

Which of the following best explains why batteries are able to generate electricity?

Accepted Answer

They convert chemical energy from redox reactions into electrical energy.

Question 12

In a redox reaction, which of the following statements is correct?

Accepted Answer

Both oxidation and reduction occur simultaneously.

Question 13

Which of the following is a common mnemonic for remembering oxidation and reduction?

Accepted Answer

LEO GER: Losing Electrons is Oxidation; Gaining Electrons is Reduction

Question 14

A reaction occurs in which the oxidation number of an element decreases. What does this indicate?

Accepted Answer

The element is reduced.

Question 15

Which of the following real-world applications relies on redox reactions?

Accepted Answer

The operation of rechargeable batteries in electric vehicles.

Question 16

If the oxidation number of nickel changes from $$+4 to$$ $$+2 in a $$reaction, what process has nickel undergone?

Accepted Answer

Reduction

Question 17

Which of the following best describes the sum of oxidation numbers in a polyatomic ion?

Accepted Answer

It equals the charge on the ion.

Question 18

In the context of corrosion, such as the rusting of iron, which process is primarily responsible for the deterioration of the metal?

Accepted Answer

Oxidation of iron atoms.

Question 19

Which of the following is NOT a rule for assigning oxidation numbers?

Accepted Answer

The oxidation number of hydrogen is always $$+1.$$

Question 20

A patient receives an electric shock that disrupts the electrochemical signals in their nervous system. Which chemical principle is most directly involved?

Accepted Answer

Redox reactions involving ions across nerve cell membranes.

Electrochemistry: Oxidation-Reduction Reactions and Agents

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