🧪 CHEMISTRY MOCK EXAM (Grade 9–10) Topics Covered: Atoms & Molecules · Atomic Structure · Metals & Non-Metals · Bonding · Gases & Gas Tests · Types

Water

A compound that contains hydrogen and oxygen chemically bonded.

Oxygen (hospital use)

A molecule of an element.

Iron

A substance that contains only one type of atom.

Air

A physical mixture of gases.

Atom neutrality

An atom is electrically neutral because the number of protons equals the number of electrons.

Atomic number

Represents the number of protons in an element.

Isotopes

Isotopes show similar chemical behavior because they have the same number of electrons.

Positive ion

What an atom becomes when it loses one electron.

Oxygen (electron shells)

An atom showing 2 electrons in the first shell and 6 in the second shell.

Neutral atom

An atom with 11 protons, 12 neutrons, and 11 electrons.

Aluminium

A material used to make aircraft, known for being strong and lightweight.

Copper

A metal used for electrical wiring, known for its ability to conduct electricity well.

Chlorine

A non-metal commonly used to disinfect drinking water.

Metals

Can conduct electricity due to delocalized electrons.

Lattice of metal ions

Explains the property of electrical conductivity in metals.

Sodium chloride

Forms when sodium transfers electrons to chlorine.

Sugar in water

Dissolves in water but does not conduct electricity because it is a covalent substance.

Low melting point compounds

CO₂ is most likely to have a low melting point.

Covalent bonds

Usually form between non-metals.

Single covalent bond

Represents two non-metal atoms sharing two pairs of electrons.

Gas particles

Move freely and randomly, unlike solid particles.

Increasing temperature of gas

Causes particles to move faster.

Oxygen test

Gas that relights a glowing splint.

Limewater test

Gas that turns limewater milky is carbon dioxide.

POP sound

Produced by hydrogen gas when a lighted splint is introduced.

Downward displacement of air

Method for collecting gases like helium.

Rusting of iron

An example of oxidation.

Natural gas burning

An example of a combustion reaction.

Acid and base reaction

Example of neutralization in antacid tablets.

Zinc and copper sulfate

A displacement reaction that produces copper metal.

Food spoilage in warm weather

Faster due to increased reaction rate.

Reaction rate of powdered solids

React faster than larger chunks because of larger surface area.

Catalyst function

Increases reaction rate by lowering activation energy.

Steeper curve on graph

Indicates lower concentration of a gas reaction.

Oxidation definition

Loss of electrons.

Reduction definition

Always involves gain of electrons.

Battery

Works due to redox reactions.

Electrons movement

From zinc to copper ions signifies zinc is oxidized.

Battery energy production

Results from redox reactions.

Electroplating purpose

Mainly used to prevent corrosion.

Electrolysis requirement

Requires a substance that conducts electricity.

Galvanization

Coating iron with zinc.

Balancing chemical equations

Important to conserve mass.

Limiting reactant

The reactant that runs out first in a chemical reaction.

Mole concept

Helps chemists count particles indirectly.

Limiting reactant in manufacturing

Determines the maximum yield.

Chemical bonds

Atoms form these to achieve stable electron arrangements.

Ionic bonds

Most likely formed by sodium and chlorine.

Electron transfer in ionic bonding

Electrons are transferred during ionic bonding.

Covalent bond characteristic

Electrons are shared between two non-metal atoms.

Ionic compounds conductivity

They conduct electricity when molten.

Soft and low boiling point substance

CO₂ is most likely to be soft and have a low boiling point.

Non-conductive substance

Solid sugar will NOT conduct electricity in any state.

Graphite conductivity

Conducts electricity due to free-moving electrons.

Diamond hardness

Due to its giant covalent structure.

Covalent bonding examples

CO₂ and H₂O both have covalent bonding.

High melting point and conductivity

Indicates ionic bonding.

Strength of ionic bond

Increased by raising ion charge.