Elements, compounds and formulae test questions - WJEC - GCSE Chemistry (Single Science) Revision

1

What is an element?

A substance made of two or more different substances that are not chemically joined together

A substance made of only one type of atom

A substance made of two or more different elements that are chemically joined together

2

What is the most accurate description of a compound?

A substance made of two or more different elements that are chemically joined together

A substance made of only one type of atom

A substance made of two or more different elements that are not chemically joined together

3

Which of the following is the correct formula for the following diagram?

Diagram of a molecule made up of one large atom and four small atoms.

CH4

CH⁴

CH₄

4

What is the formula of the compound aluminium oxide, given that the aluminium ion is Al³⁺ and the oxide ion is O^2–?

AlO

Al₃O₂

Al₂O₃

5

When an atom loses two electrons, what charge would the ion be?

+

2+

2–

6

What is the chemical symbol for sodium?

Na

NA

S

7

How many carbon atoms are there in sodium carbonate (Na₂CO₃)?

One

Two

Three

8

What is the chemical formula for a molecule of chlorine gas?

Cl

Cl₂

Cl2

9

How many atoms, in total, are present in potassium sulfate, K₂SO₄?

Seven

Six

Three

10

What is the the chemical formula for barium hydroxide (which contains the ions Ba²⁺ and OH^–)?

Ba₂OH

BaOH₂

Ba(OH)₂