Y9 CHEM REVIEW MONDAY

What is the smallest unit of an element that retains its properties?

• Molecule

• Atom

• Compound

• Mixture

Which of the following is a pure substance?

• Saltwater

• Oxygen gas (O₂)

• Trail mix

• Air

A physical change involves:

• Formation of new substances

• Changes in molecular composition

• Altering shape or state (e.g., melting ice)

• Release of energy as light

What type of change is rusting iron?

• Physical

• Chemical

• Both

• Neither

Match the following chemical symbols with their corresponding chemical names.

• Glucose

• CO₂

• Water

• H₂O

• Carbon dioxide

• Fe₂O₃

• Iron(III) oxide

• C₆H₁₂O₆

• Table salt

• NaCl

In the reaction 2H₂ + O₂ → 2H₂O, the coefficient "2" before H₂O indicates:

• 2 atoms of water

• 2 molecules of water

• 2 grams of water

• 2 litres of water

Which process is a physical change?

• Photosynthesis

• Dissolving sugar in tea

• Digestion of food

• Neutralising acid with base

Which Law states that: mass is neither created nor destroyed in a chemical reaction?

(a)  

Which is evidence of a chemical change? Pick more than two options and fewer than four.

• Change in temperature

• Formation of a precipitate

• Change in state

• Change in density

• Formation of a gas

In the reaction CH₄ + 2O₂ → CO₂ + 2H₂O, how many oxygen atoms are on the product side?

• 2

• 4

• 6

• 8