Chemical Reactions: Types, Balancing, and More | Year 12 Chemistry

Question 1

Which of the following is the limiting reactant in the reaction: 2Cu + O₂ → 2CuO, if 0.5 mol of Cu and 0.25 mol of O₂ are present?

Accepted Answer

O₂

Answer

Cu

Answer

Neither

Answer

Not enough information provided

Question 2

Which of the following is a catalyst?

Accepted Answer

A substance that speeds up a reaction and is not consumed in the process

Answer

A substance that speeds up a reaction and is consumed in the process

Answer

A substance that slows down a reaction and is consumed in the process

Answer

A substance that slows down a reaction and is not consumed in the process

Question 3

Which of the following reactions is an example of an exothermic reaction?

Accepted Answer

A reaction that releases heat

Answer

A reaction that absorbs heat

Answer

A reaction that has no change in temperature

Answer

A reaction that decreases in temperature

Question 4

What is the pH of a 0.01 M solution of NaOH?

Accepted Answer

13

Answer

0

Answer

1

Answer

7

Question 5

Consider the following equation: 2Fe + 3Cl₂ → 2FeCl₃. What is the coefficient in front of Fe?

Accepted Answer

2

Answer

3

Answer

6

Answer

9

Question 6

What is the effect of adding a catalyst to a chemical reaction?

Accepted Answer

It lowers the activation energy of the reaction

Answer

It changes the products of the reaction

Answer

It shifts the equilibrium position

Answer

It increases the rate of the forward reaction but not the reverse reaction

Question 7

Which of the following substances is NOT a catalyst?

Accepted Answer

Sodium hydroxide

Answer

Nickel

Answer

Enzymes

Answer

Platinum

Question 8

At equilibrium, the concentrations of reactants and products remain constant.

Accepted Answer

True

Answer

False

Question 9

The standard enthalpy change of a reaction is positive. This indicates that:

Accepted Answer

The reaction is endothermic

Answer

The reaction is exothermic

Answer

The reaction has no enthalpy change

Answer

The reaction is spontaneous

Question 10

In the reaction 2H2 + O2 → 2H2O, the mole ratio of hydrogen to oxygen atoms is:

Accepted Answer

1:2

Answer

1:1

Answer

2:1

Answer

2:2

Question 11

Which factor does **not** affect the rate of a chemical reaction?

Accepted Answer

Identity of the reactants

Answer

Temperature

Answer

Surface area of reactants

Answer

Concentration of reactants

Question 12

At equilibrium, the rate of the forward reaction is:

Accepted Answer

Equal to the rate of the reverse reaction

Answer

Faster than the rate of the reverse reaction

Answer

Slower than the rate of the reverse reaction

Question 13

Which of the following substances acts as a catalyst in chemical reactions?

Accepted Answer

Platinum in a catalytic converter

Answer

Sodium chloride dissolved in water

Answer

Water in a hydrolysis reaction

Answer

Carbon dioxide in the atmosphere

Question 14

In an endothermic reaction, heat is:

Accepted Answer

Absorbed

Answer

Released

Answer

Neither released nor absorbed

Question 15

What is the standard enthalpy change of formation for an element in its standard state?

Accepted Answer

0 kJ/mol

Answer

Positive value

Answer

Negative value

Question 16

Which of the following is not a type of chemical reaction encountered in inorganic chemistry?

Accepted Answer

Transmutation

Answer

Combination

Answer

Decomposition

Answer

Neutralization

Question 17

Balance the following equation: 2Fe + 6HCl → FeCl₃ + 3H₂

Accepted Answer

2Fe + 6HCl → 2FeCl₃ + 3H₂

Answer

Fe + 2HCl → FeCl₂ + H₂

Answer

2Fe + 4HCl → 2FeCl₂ + 2H₂

Answer

Fe + HCl → FeCl + HH

Question 18

Which of the following reactions is endothermic?

Accepted Answer

Dissolving ammonium chloride in water

Answer

Combustion of propane

Answer

Neutralization of an acid and a base

Answer

Precipitation of barium sulfate

Question 19

Which of the following is a Lewis acid?

Accepted Answer

BF₃

Answer

NH₃

Answer

H₂O

Answer

OH⁻

Question 20

In a reaction between 2 moles of methane (CH4) and 3 moles of oxygen (O2), which reactant is limiting?

Accepted Answer

Methane (CH4)

Answer

Oxygen (O2)

Answer

Neither reactant is limiting

Answer

Both reactants are limiting

Question 21

Which reaction type involves the transfer of electrons between reactants?

Accepted Answer

Redox reaction

Answer

Acid-base reaction

Answer

Precipitation reaction

Answer

Combustion reaction

Question 22

What type of reaction occurs when an acid reacts with a base?

Accepted Answer

Neutralization

Answer

Precipitation

Answer

Combustion

Answer

Redox

Question 23

Which substance dissociates completely in water, forming ions?

Accepted Answer

Hydrochloric acid (HCl)

Answer

Acetic acid (CH3COOH)

Answer

Ammonia (NH3)

Answer

Water (H2O)

Question 24

What is the pH of a solution with a hydroxide ion concentration of 1 x 10^-9 M?

Accepted Answer

9

Answer

5

Answer

7

Answer

14

Question 25

Which factor does NOT influence the rate of a chemical reaction?

Accepted Answer

Magnetic field strength

Answer

Surface area of solids

Answer

Temperature

Answer

Concentration of reactants

Question 26

Which reaction is an example of a redox reaction?

Accepted Answer

2NH3 + 3CuO -> 3Cu + 3H2O + N2

Answer

NaOH + HCl -> NaCl + H2O

Answer

2HCl + Mg -> MgCl2 + H2

Answer

CH4 + 2O2 -> CO2 + 2H2O

Question 27

Which species is the conjugate acid of NH3?

Accepted Answer

NH4+

Answer

NH2-

Answer

NO3-

Answer

H2O

Question 28

How do the surface area of reactants, temperature, and concentration influence the rate of a chemical reaction? Provide specific examples to support your explanation.

Accepted Answer

Increasing surface area, temperature, and concentration all accelerate the reaction rate.

Answer

Surface area, temperature, and concentration have no impact on reaction rates.

Answer

Increasing surface area and concentration slows down the reaction rate, while increasing temperature speeds it up.

Answer

Increasing surface area slows down the reaction rate, while increasing temperature and concentration speed it up.

Question 29

Which of the following is a characteristic of a chemical change?

Accepted Answer

Formation of a new substance with different properties

Answer

Change in state only

Answer

Change in color only

Answer

Dissolving in a solvent

Question 30

In an equilibrium reaction, the forward and reverse reactions occur at the same rate resulting in:

Accepted Answer

No net change in the concentrations of reactants and products

Answer

Only the forward reaction occurs

Answer

Only the reverse reaction occurs

Question 31

Which of the following is NOT a function of a catalyst?

Accepted Answer

Altering the products of a reaction

Answer

Providing an alternative pathway for the reaction

Answer

Increasing the rate of a reaction

Answer

Lowering the activation energy of a reaction

Question 32

Which of the following processes is exothermic?

Accepted Answer

Combustion of propane

Answer

Evaporation of water

Answer

Dissolution of sugar in water

Answer

Melting of ice

Question 33

Which of the following is NOT a type of chemical reaction?

Accepted Answer

Nuclear reaction

Answer

Neutralization reaction

Answer

Decomposition reaction

Answer

Single-replacement reaction

Question 34

In a chemical reaction, the limiting reactant is the reactant that:

Accepted Answer

Is completely consumed first

Answer

Is present in excess

Answer

Has the highest concentration

Answer

Reacts at the slowest rate

Question 35

Chemical equilibrium is a state of balance where:

Accepted Answer

The forward and reverse reactions occur at the same rate

Answer

The products are completely formed

Answer

The reactants are completely consumed

Question 36

The enthalpy change of a reaction is the:

Accepted Answer

Heat energy absorbed or released during the reaction

Answer

Change in free energy of the reaction

Answer

Change in entropy of the reaction

Question 37

The activation energy of a reaction is the:

Accepted Answer

Minimum energy required for a reaction to occur

Answer

Difference in energy between the reactants and products

Answer

Maximum energy released by a reaction

Question 38

Which of the following reactions is a radioactive decay?

Accepted Answer

¹⁴C → ¹⁴N + β⁻

Answer

AgNO₃ + NaCl → AgCl + NaNO₃

Answer

CH₄ + 2O₂ → CO₂ + 2H₂O

Answer

NaOH + HCl → NaCl + H₂O

Question 39

Balance the following equation: 2Fe + 6HCl → ?

Accepted Answer

2Fe + 6HCl → 2FeCl₃ + 3H₂

Answer

2Fe + 3HCl → FeCl₃ + 3H₂

Answer

2Fe + 6HCl → FeCl₂ + 3H₂

Answer

Fe + 6HCl → FeCl₃ + 3H₂

Question 40

Which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

Age of the reactants

Answer

Temperature

Answer

Concentration of the reactants

Answer

Surface area of the reactants

Question 41

Which of the following expressions represents the equilibrium constant for the reaction: N₂(g) + 3H₂(g) ⇌ 2NH₃(g)?

Accepted Answer

K = [NH₃]²/[N₂][H₂]³

Answer

K = [NH₃]/[N₂][H₂]

Answer

K = [H₂]³/[NH₃]²/[N₂]

Answer

K = [N₂]/[NH₃][H₂]

Question 42

An enzyme is an example of a:

Accepted Answer

Catalyst

Answer

Reactant

Answer

Product

Answer

Inhibitor