G11 Chemistry Term 3 Exam Review

What is the total number of protons, neutrons, and electrons in an oxygen-18

isotope?

• 8 protons, 10 neutrons, 8 electrons

• 10 protons, 8 neutrons, 8 electrons

• 8 protons, 8 neutrons, 10 electrons

• 9 protons, 9 neutrons, 8 electrons

Answer explanation

An isotope is an atom of the same element that has a different number of neutrons but the same number of protons and electrons as a neutral atom.

The atomic number of oxygen is 8, which means that every oxygen atom, regardless of isotope, must have 8 protons.

Which of the following correctly represents a single-replacement reaction?

• H2 + O2 → H2O

• Zn + CuSO4 → ZnSO4 + Cu

• NaCl + AgNO3 → NaNO3 + AgCl

• C6H12O6 + O2 → CO2 + H2O

Answer explanation

A single-replacement reaction (also called a single-displacement reaction) occurs when one element replaces another in a compound.

The general formula is:

A+BC→AC+BA + BC → AC + BA+BC→AC+B

In reaction (b):

Zn (zinc) is a single element that replaces Cu (copper) in CuSO₄ (copper sulfate).

This produces ZnSO₄ (zinc sulfate) and Cu (solid copper).

Which gas law describes the relationship between pressure and volume?

• Charles’s Law

• Boyle’s Law

• Avogadro’s Law

• Ideal Gas Law

Answer explanation

Boyle’s Law states that pressure (P) and volume (V) are inversely related when temperature and the number of gas particles remain constant.

Mathematical Formula: P1​V1​=P2​V2​

If pressure increases, volume decreases.

If pressure decreases, volume increases.

Examples:

When you squeeze a balloon, the pressure inside increases, causing the volume to decrease.

When you release the pressure, the balloon expands again.

The type of bond in NaCl is:

• Covalent

• Metallic

• Hydrogen

• Ionic

Answer explanation

NaCl (sodium chloride) is an ionic compound because it forms from the transfer of electrons between a metal (Na) and a non-metal (Cl).

Sodium (Na) is a metal that loses one electron to form a Na⁺ ion.

Chlorine (Cl) is a non-metal that gains one electron to form a Cl⁻ ion.

The opposite charges (Na⁺ and Cl⁻) attract, forming a strong ionic bond.

5.What is the correct molecular shape of CO2?

• Bent

• Trigonal pyramidal

• Linear

• Tetrahedral

Answer explanation

Carbon dioxide (CO₂) has a linear molecular shape because:

The central carbon (C) atom forms two double bonds with oxygen (O).

The molecule has no lone pairs on the central carbon, meaning the two oxygen atoms arrange themselves as far apart as possible.

The bond angle is 180°, resulting in a straight linear structure.

6.Which of the following phase changes is exothermic?

• Melting

• Evaporation

• Condensation

• Sublimation

Answer explanation

An exothermic process releases heat into the surroundings.

Condensation is the process where gas turns into a liquid, releasing heat as molecules lose energy and slow down.

Example: Water vapor condensing into droplets on a cold surface releases heat.

Which element has the highest electronegativity?

• Sodium

• Fluorine

• Carbon

• Sulfur

Answer explanation

Electronegativity is a measure of an atom’s ability to attract electrons in a chemical bond.

Fluorine (F) has the highest electronegativity (3.98) on the Pauling scale, because:

It has a small atomic radius, meaning electrons are strongly attracted to the nucleus.

It needs only one more electron to complete its octet, making it highly reactive.

It has a high nuclear charge relative to its size, increasing attraction for electrons.

If the volume of a gas is decreased while keeping temperature constant, what

happens to the pressure?

• Increases

• Decreases

• Stays the same

Answer explanation

This follows Boyle’s Law, which states that pressure (P) and volume (V) are inversely related when temperature remains constant.

Boyle’s Law Equation: P1​V1​=P2​V2​

If volume decreases, the particles are compressed, leading to more collisions, which increases pressure.

Example: Squeezing a balloon reduces its volume, making the air inside more pressurized.

What is the term for the amount of energy required to raise the temperature of 1

gram of a substance by 1°C?

• Enthalpy

• Specific heat capacity

• Activation energy

• Heat of formation

Answer explanation

Specific heat capacity is the amount of energy (heat) required to raise the temperature of 1 gram of a substance by 1°C.

It is represented by C in the formula: q=mcΔT

Where:

q = heat energy (Joules)

m = mass (grams)

C = specific heat capacity (J/g°C)

ΔT = change in temperature (°C)

Example: Water has a high specific heat capacity (4.18 J/g°C), meaning it takes a lot of energy to heat up or cool down.

Which intermolecular force is the strongest?

• London dispersion forces

• Dipole-dipole interactions

• Hydrogen bonding

• Van der Waals forces

Answer explanation

Intermolecular forces (IMFs) are forces between molecules that determine boiling points, melting points, and solubility.

Hydrogen bonding is the strongest intermolecular force because:

It occurs when hydrogen (H) is bonded to a highly electronegative atom (N, O, or F).

This creates a strong partial positive charge on hydrogen, allowing strong attractions between molecules.

Example: Water (H₂O) molecules form hydrogen bonds, making water’s boiling point higher than expected.