Question 1

A student is given a sample of an unknown metal and is asked to determine whether it is a pure element or a mixture. Which experimental technique would be most appropriate to confirm its purity?
Correct answer: Measuring its melting point and comparing it to the known value for the pure element.

Accepted Answer

Measuring its melting point and comparing it to the known value for the pure element.

Question 2

Which of the following best explains why sodium chloride conducts 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 3

A chemist is analyzing a sample of chlorine gas, which consists of two isotopes: 35Cl (75%) and 37Cl (25%). What is the relative atomic mass of chlorine?
Correct answer: 35.5

Accepted Answer

35.5

Question 4

Which of the following statements about covalent and ionic bonding is correct?
Correct answer: Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 5

A student is asked to write the electron configuration for a magnesium atom. Which of the following is correct?
Correct answer: 2,8,2

Accepted Answer

2,8,2

Question 6

During a laboratory experiment, a student mixes hydrochloric acid with sodium hydroxide. Which type of chemical reaction is this, and what is the main product formed?
Correct answer: Neutralization; water

Accepted Answer

Neutralization; water

Question 7

Which of the following best describes why metals are good conductors of electricity?
Correct answer: They have delocalized electrons that can move freely throughout the structure.

Accepted Answer

They have delocalized electrons that can move freely throughout the structure.

Question 8

A student is given a mixture of sand and salt. Which sequence of experimental techniques would best separate the two substances?
Correct answer: Dissolve in water, filter, then evaporate the filtrate.

Accepted Answer

Dissolve in water, filter, then evaporate the filtrate.

Question 9

Which of the following is a correct balanced chemical equation for the reaction between magnesium and hydrochloric acid?
Correct answer: Mg + 2HCl → MgCl2 + H2

Accepted Answer

Mg + 2HCl → MgCl2 + H2

Question 10

Which of the following best explains why ice floats on water?
Correct answer: Ice is less dense than liquid water due to its open lattice structure.

Accepted Answer

Ice is less dense than liquid water due to its open lattice structure.

Question 11

A student is asked to suggest an improvement to an experiment that measures the rate of reaction between calcium carbonate and hydrochloric acid. Which suggestion would best improve the accuracy of the results?
Correct answer: Use a gas syringe to measure the volume of carbon dioxide produced.

Accepted Answer

Use a gas syringe to measure the volume of carbon dioxide produced.

Question 12

Which of the following environmental issues is most directly related to the combustion of fossil fuels?
Correct answer: Acid rain

Accepted Answer

Acid rain

Question 13

A sample of ethene (C2H4) is burned completely in oxygen. Which products are formed?
Correct answer: Carbon dioxide and water

Accepted Answer

Carbon dioxide and water

Question 14

Which of the following best describes the role of a catalyst in a chemical reaction?
Correct answer: It lowers the activation energy, increasing the rate of reaction without being consumed.

Accepted Answer

It lowers the activation energy, increasing the rate of reaction without being consumed.

Question 15

A student is asked to identify an unknown solution as either an acid or a base. Which method would provide the most reliable result?
Correct answer: Measure the pH using a pH meter.

Accepted Answer

Measure the pH using a pH meter.

Question 16

Which of the following statements 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 17

A student is asked to explain why diamond has a much higher melting point than graphite, even though both are forms of carbon. Which explanation is correct?
Correct answer: Diamond has a three-dimensional covalent network, requiring more energy to break all the bonds.

Accepted Answer

Diamond has a three-dimensional covalent network, requiring more energy to break all the bonds.

Question 18

Which of the following is the best example of a redox reaction?
Correct answer: Zinc metal reacting with copper(II) sulfate to produce copper and zinc sulfate.

Accepted Answer

Zinc metal reacting with copper(II) sulfate to produce copper and zinc sulfate.

Question 19

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

Question 20

Which of the following best describes a safe laboratory practice 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.

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards