Chemistry level 7 Quiz

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

• Melting of ice

• Colour change

• Breaking a glass

• Dissolving sugar in water

What is the main difference between a pure substance and a mixture?

• Pure substances have a uniform composition, mixtures do not.

• Mixtures have a uniform composition, pure substances do not.

• Pure substances can be separated by physical means, mixtures cannot.

• Mixtures are always liquids, pure substances are always solids.

Which of the following is an example of a homogeneous mixture?

• Sand and water

• Oil and water

• Salt dissolved in water

• A salad

Which technique would you use to separate a mixture of sand and iron filings?

• Filtration

• Evaporation

• Magnetic separation

• Distillation

What is the laboratory test for the presence of carbon dioxide gas?

• It turns limewater milky.

• It pops a glowing splint.

• It extinguishes a burning splint.

• It changes the colour of litmus paper.

Which of the following is a chemical change?

• Boiling water

• Rusting of iron

• Cutting paper

• Freezing water

What is the process of separating a solid from a liquid by pouring off the liquid called?

• Filtration

• Decantation

• Crystallisation

• Chromatography

Which of the following is a pure substance?

• Air

• Saltwater

• Gold

• Milk

What is the main characteristic of a heterogeneous mixture?

• It has a uniform composition throughout.

• It has a non-uniform composition.

• It cannot be separated by physical means.

• It is always a liquid.

Which separation technique is best for obtaining pure water from saltwater?

• Filtration

• Evaporation

• Distillation

• Crystallisation