Question 1

Which of the following statements best describes the role of sodium (Na) in a redox reaction with chlorine (Cl$$_2$$)?

Accepted Answer

Sodium acts as the reductant and loses electrons.

Question 2

In the reaction $$\mathrm{Cu(s) + 2AgNO_3(aq) \rightarrow Cu(NO_3$)_2(aq) + 2Ag(s)}$$, which species is oxidized?

Accepted Answer

Cu(s)

Question 3

What is the oxidation number of chlorine in $$\mathrm{$$ClO_3$$^-}$$?

Accepted Answer

$$+5$$

Question 4

Which of the following is a correct balanced redox reaction?

Accepted Answer

$$\mathrm{Al(s) + Cu$$^{2+}$$(aq) \rightarrow Cu(s) + Al$$^{3+}$$(aq)}$$

Question 5

In the combustion of octane, $$\mathrm{C_8H_{18} + 25O_2 \rightarrow 16CO_2 + 18H_2O}$$, which element is reduced?

Accepted Answer

Oxygen

Question 6

Which of the following compounds contains an atom with an oxidation number of $$-2$$?

Accepted Answer

$$\mathrm{H_2O}$$

Question 7

Given the reaction $$\mathrm{H_2O \rightarrow 2H_2 + O_2$}$$, what is the change in oxidation number for oxygen?

Accepted Answer

From $$-2 to$$ $$0$$

Question 8

Which statement about oxidation numbers is correct?

Accepted Answer

The sum of oxidation numbers in a neutral compound is always zero.

Question 9

In the reaction $$\mathrm{Cu(s) + 2AgNO_3(aq) \rightarrow Cu(NO_3$)_2(aq) + 2Ag(s)}$$, which species is the oxidant?

Accepted Answer

AgNO$$_3$$

Question 10

Which of the following is a real-world application of chlorine's oxidizing properties?

Accepted Answer

Used as a bleach and disinfectant

Question 11

What is the oxidation number of oxygen in $$\mathrm{SO_4$^{2-}}$$?

Accepted Answer

$$-2$$

Question 12

Which of the following best describes the process of reduction?

Accepted Answer

Gain of electrons by an atom or ion

Question 13

In the reaction $$\mathrm{C_7H_5N_3O_6 + 21/2 O_2$ \rightarrow 3 N_2$ + 5 H_2O + 14 CO_2$}$$, which element undergoes oxidation?

Accepted Answer

Carbon

Question 14

Which of the following is the correct oxidation number for hydrogen in $$\mathrm{NH_3$}$$?

Accepted Answer

$$+1$$

Question 15

What is the oxidation number of chromium in $$\mathrm{Cr_2O_7$$^{2-}$$}$$?

Accepted Answer

$$+6$$

Question 16

Which of the following is a correct statement about the oxidation number of elements in their standard state?

Accepted Answer

It is always zero.

Question 17

In the reaction $$\mathrm{H_2O \rightarrow 2H_2 + O_2$}$$, which species is the reductant?

Accepted Answer

H$$_2O$$

Question 18

Which of the following is a common misconception about oxidation numbers?

Accepted Answer

The oxidation number of an element in a compound is always equal to its group number.

Question 19

Which of the following reactions demonstrates the use of sodium as a coolant in nuclear reactors?

Accepted Answer

Na(s) is used in liquid form to transfer heat without undergoing a chemical reaction.

Introduction to Oxidation-Reduction (Redox) Reactions

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