25-minute Test : Part I Planet Earth

Which of the following processes is a chemical change?

• A. Crystallization of sea water
• B. Distillation of sea water
• C. Electrolysis of sea water
• D. Evaporation of sea water

Refer to the following set-up. What can be observed after some time?

• A. The hydrated copper(II) sulphate crystals turn from blue to white.
• B. The hydrated copper(II) sulphate crystals turn from white to blue.
• C. The hydrated copper(II) sulphate crystals turn from blue to pink.
• D. The hydrated copper(II) sulphate crystals turn from pink to blue.

Consider the following conversion. Which of the following combinations is correct?

• A
• B
• C
• D

Which of the following statements about performing a flame test is INCORRECT?

• A. Concentrated hydrochloric acid is needed.
• B. The solid sample should be heated in a luminous Bunsen flame.
• C. The solid sample should be in powdered form.
• D. A platinum wire can be used to perform the test.

Different gases in air can be separated by fractional distillation because they have different

• A. densities.
• B. boiling points.
• C. melting points.
• D. freezing points.

Solid X is subjected to three tests and the results are shown in the following table. Which of the following solids might X be?

• A. Potassium carbonate
• B. Potassium chloride
• C. Magnesium carbonate
• D. Magnesium chloride

Which of the following diagrams represents the arrangement of particles in a mixture of an element and a compound?

(Particles of different colours represent atoms of different elements.)

• A
• B
• C
• D

Which of the following methods is most suitable for obtaining pure water from sea water?

• A. Crystallization
• B. Distillation
• C. Evaporation
• D. Filtration

Which of the following combinations about metal extraction methods is correct?

• A
• B
• C
• D

Which of the following word equations is INCORRECT?

• A. calcium carbonate + hydrochloric acid → calcium chloride + carbon dioxide
• B. calcium carbonate → calcium oxide + carbon dioxide
• C. calcium hydroxide + carbon dioxide → calcium carbonate + water
• D. calcium oxide + water → calcium hydroxide