Question 1

A student is asked to separate a mixture of sand, salt, and iron filings. Which sequence of methods would most effectively separate all three components?
Correct answer: Add water, filter, use a magnet on the residue, then evaporate the filtrate.

Accepted Answer

Add water, filter, use a magnet on the residue, then evaporate the filtrate.

Question 2

Which statement best explains why graphite conducts electricity but diamond does not?
Correct answer: Graphite has delocalized electrons that can move between layers, while diamond has all electrons localized in covalent bonds.

Accepted Answer

Graphite has delocalized electrons that can move between layers, while diamond has all electrons localized in covalent bonds.

Question 3

A sample of chlorine contains two isotopes: 75% Cl-35 and 25% Cl-37. What is the relative atomic mass (Arel) of this sample?
Correct answer: 35.5

Accepted Answer

35.5

Question 4

Which of the following best describes the process of electrolysis in the extraction of aluminum from its ore?
Correct answer: Aluminum ions gain electrons at the cathode to form aluminum metal.

Accepted Answer

Aluminum ions gain electrons at the cathode to form aluminum metal.

Question 5

A student measures the temperature change when hydrochloric acid reacts with sodium hydroxide. Which type of reaction is this, and what is the expected temperature change?
Correct answer: Exothermic; temperature increases.

Accepted Answer

Exothermic; temperature increases.

Question 6

Which of the following is a correct statement about acids, bases, and salts?
Correct answer: A salt is formed when the hydrogen ion in an acid is replaced by a metal ion or ammonium ion.

Accepted Answer

A salt is formed when the hydrogen ion in an acid is replaced by a metal ion or ammonium ion.

Question 7

Which property is most likely to be observed in a giant ionic lattice such as sodium chloride?
Correct answer: High melting point and conducts electricity when molten.

Accepted Answer

High melting point and conducts electricity when molten.

Question 8

A student is asked to design an experiment to determine the effect of concentration on the rate of a chemical reaction. Which variable should be kept constant?
Correct answer: Temperature

Accepted Answer

Temperature

Question 9

Which of the following best explains why metals are malleable?
Correct answer: The layers of positive ions can slide over each other while being held together by a sea of delocalized electrons.

Accepted Answer

The layers of positive ions can slide over each other while being held together by a sea of delocalized electrons.

Question 10

Which environmental issue is most directly linked to the combustion of fossil fuels?
Correct answer: Acid rain due to the release of sulfur dioxide and nitrogen oxides.

Accepted Answer

Acid rain due to the release of sulfur dioxide and nitrogen oxides.

Question 11

A hydrocarbon undergoes complete combustion in air. Which products are formed?
Correct answer: Carbon dioxide and water

Accepted Answer

Carbon dioxide and water

Question 12

Which of the following is the best method to test for the presence of water in a sample?
Correct answer: Add anhydrous copper(II) sulfate and observe if it turns blue.

Accepted Answer

Add anhydrous copper(II) sulfate and observe if it turns blue.

Question 13

Which statement about isotopes is correct?
Correct answer: Isotopes of an element have the same number of protons but different numbers of neutrons.

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 14

A student is given a colorless solution and asked to identify the cation present. Which experimental technique should they use first?
Correct answer: Add sodium hydroxide solution and observe any precipitate formed.

Accepted Answer

Add sodium hydroxide solution and observe any precipitate formed.

Question 15

Which of the following best describes the role of a catalyst in a chemical reaction?
Correct answer: It provides an alternative pathway with lower activation energy.

Accepted Answer

It provides an alternative pathway with lower activation energy.

Question 16

Which of the following is a correct statement about the Periodic Table?
Correct answer: Elements in the same group have similar chemical properties because they have the same number of outer electrons.

Accepted Answer

Elements in the same group have similar chemical properties because they have the same number of outer electrons.

Question 17

A student is asked to suggest an improvement to an experiment that produced inconsistent results due to temperature fluctuations. Which suggestion is most appropriate?
Correct answer: Use a water bath to maintain a constant temperature during the experiment.

Accepted Answer

Use a water bath to maintain a constant temperature during the experiment.

Question 18

Which of the following best explains why ionic compounds conduct electricity when molten but not when solid?
Correct answer: Ions are free to move in the molten state but fixed in the solid state.

Accepted Answer

Ions are free to move in the molten state but fixed in the solid state.

Question 19

Which of the following is a correct safety precaution when heating a substance in a test tube?
Correct answer: Point the mouth of the test tube away from yourself and others.

Accepted Answer

Point the mouth of the test tube away from yourself and others.

Question 20

A student is asked to calculate the empirical formula of a compound containing 40% sulfur and 60% oxygen by mass. What is the empirical formula?
Correct answer: SO3

Accepted Answer

SO3

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards