Question 1

A student is asked to explain why sodium chloride (NaCl) conducts electricity when molten but not when solid. Which explanation best applies?
Correct answer: In the molten state, sodium and chloride ions are mobile and can carry an electric current.

Accepted Answer

In the molten state, sodium and chloride ions are mobile and can carry an electric current.

Question 2

Which of the following best describes the process of diffusion as explained by the kinetic particle theory?
Correct answer: Particles move randomly, spreading from regions of high concentration to low concentration until evenly distributed.

Accepted Answer

Particles move randomly, spreading from regions of high concentration to low concentration until evenly distributed.

Question 3

A chemist is designing an experiment to determine the purity of a sample of aspirin. Which technique would be most appropriate?
Correct answer: Measuring the melting point and comparing it to the pure substance.

Accepted Answer

Measuring the melting point and comparing it to the pure substance.

Question 4

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 5

A student mixes hydrochloric acid with sodium hydroxide in a beaker. The temperature of the solution increases. What type of reaction is this, and what does the temperature change indicate?
Correct answer: It is an exothermic reaction; heat is released to the surroundings.

Accepted Answer

It is an exothermic reaction; heat is released to the surroundings.

Question 6

Which of the following best explains why metals are good conductors of electricity?
Correct answer: Metals have free-moving delocalized electrons that carry charge.

Accepted Answer

Metals have free-moving delocalized electrons that carry charge.

Question 7

A sample contains 75% isotope X (mass 24) and 25% isotope Y (mass 26). What is the relative atomic mass of the element?
Correct answer: 24.5

Accepted Answer

24.5

Question 8

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

Accepted Answer

Mg + 2HCl → MgCl2 + H2

Question 9

Which of the following best describes the environmental impact of excessive use of nitrogen-based fertilizers?
Correct answer: They lead to eutrophication, causing algal blooms and oxygen depletion in water bodies.

Accepted Answer

They lead to eutrophication, causing algal blooms and oxygen depletion in water bodies.

Question 10

A student is asked to separate a mixture of sand and salt. Which sequence of techniques should be used?
Correct answer: Dissolve in water, filter, evaporate the filtrate.

Accepted Answer

Dissolve in water, filter, evaporate the filtrate.

Question 11

Which of the following statements about the Periodic Table is correct?
Correct answer: Elements in the same group have similar chemical properties due to the same number of valence electrons.

Accepted Answer

Elements in the same group have similar chemical properties due to the same number of valence electrons.

Question 12

Which of the following is a property of ionic compounds?
Correct answer: They conduct electricity when dissolved in water.

Accepted Answer

They conduct electricity when dissolved in water.

Question 13

A student is asked to design an experiment to compare the reactivity of three metals: magnesium, zinc, and copper, with dilute hydrochloric acid. Which observation would best indicate the order of reactivity?
Correct answer: The rate at which each metal dissolves and the amount of hydrogen gas produced.

Accepted Answer

The rate at which each metal dissolves and the amount of hydrogen gas produced.

Question 14

Which of the following best explains why diamond is hard and has a high melting point?
Correct answer: Diamond has a giant covalent structure with each carbon atom bonded to four others.

Accepted Answer

Diamond has a giant covalent structure with each carbon atom bonded to four others.

Question 15

Which of the following is a correct statement about acids and bases?
Correct answer: Acids donate protons (H+) and bases accept protons.

Accepted Answer

Acids donate protons (H+) and bases accept protons.

Question 16

A student is asked to calculate the empirical formula of a compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula?
Correct answer: CH2O

Accepted Answer

CH2O

Question 17

Which of the following best describes the process of electrolysis of molten lead(II) bromide?
Correct answer: Lead ions are reduced at the cathode and bromide ions are oxidized at the anode.

Accepted Answer

Lead ions are reduced at the cathode and bromide ions are oxidized at the anode.

Question 18

Which of the following is a correct example of a redox reaction?
Correct answer: Zinc reacts with copper(II) sulfate to form zinc sulfate and copper.

Accepted Answer

Zinc reacts with copper(II) sulfate to form zinc sulfate and copper.

Question 19

Which of the following best explains why water is a good solvent for ionic compounds?
Correct answer: Water molecules are polar and can surround and separate ions.

Accepted Answer

Water molecules are polar and can surround and separate ions.

Question 20

A student is asked to evaluate the safety of a proposed experiment involving concentrated sulfuric acid. Which of the following is the most important safety precaution?
Correct answer: Always add acid to water, not water to acid, to prevent splashing.

Accepted Answer

Always add acid to water, not water to acid, to prevent splashing.

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards