Question 1

Which of the following best explains why sodium chloride (NaCl) conducts electricity when dissolved in water but not in its solid state?
Correct answer: In aqueous solution, Na+ and Cl- ions are free to move and carry electric current.

Accepted Answer

In aqueous solution, Na+ and Cl- ions are free to move and carry electric current.

Question 2

A student is asked to determine the empirical formula of a compound containing only carbon and hydrogen. She combusts 0.50 g of the compound and obtains 1.65 g of CO2 and 0.90 g of H2O. What is the empirical formula of the compound?
Correct answer: CH4

Accepted Answer

CH4

Question 3

Which of the following statements about isotopes is correct?
Correct answer: Isotopes of an element have identical chemical properties but different physical properties.

Accepted Answer

Isotopes of an element have identical chemical properties but different physical properties.

Question 4

A sample of gas is compressed at constant temperature. According to the kinetic particle theory, what happens to the average kinetic energy and the frequency of collisions between gas particles?
Correct answer: Average kinetic energy remains the same; frequency of collisions increases.

Accepted Answer

Average kinetic energy remains the same; frequency of collisions increases.

Question 5

Which of the following best describes the process of diffusion in gases?
Correct answer: Particles move randomly, resulting in the net movement from high to low concentration.

Accepted Answer

Particles move randomly, resulting in the net movement from high to low concentration.

Question 6

A student is asked to prepare a salt by reacting an acid with a metal. Which of the following combinations will NOT produce a salt?
Correct answer: Hydrochloric acid and copper

Accepted Answer

Hydrochloric acid and copper

Question 7

Which of the following best explains why diamond has a much higher melting point than graphite?
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 8

A chemical plant is considering two methods for producing hydrogen gas: electrolysis of water and reaction of zinc with hydrochloric acid. Which factor should be considered when choosing the more environmentally friendly method?
Correct answer: The amount of energy required and the by-products generated.

Accepted Answer

The amount of energy required and the by-products generated.

Question 9

Which of the following is the correct balanced equation for the reaction between aluminum and oxygen to form aluminum oxide?
Correct answer: 4Al + 3O2 → 2Al2O3

Accepted Answer

4Al + 3O2 → 2Al2O3

Question 10

A student is asked to calculate the number of moles in 18 g of water (H2O). (Relative atomic masses: H = 1, O = 16)
Correct answer: 1.0 mol

Accepted Answer

1.0 mol

Question 11

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.

Accepted Answer

It lowers the activation energy, increasing the rate of reaction.

Question 12

Which of the following is a correct statement about metals in the Periodic Table?
Correct answer: Metals tend to lose electrons to form positive ions.

Accepted Answer

Metals tend to lose electrons to form positive ions.

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 most reactive metal?
Correct answer: The metal that produces the most gas bubbles in the shortest time.

Accepted Answer

The metal that produces the most gas bubbles in the shortest time.

Question 14

Which of the following is a correct description of an exothermic reaction?
Correct answer: A reaction that releases heat to the surroundings.

Accepted Answer

A reaction that releases heat to the surroundings.

Question 15

Which of the following best explains why carbon monoxide (CO) is considered a pollutant in the environment?
Correct answer: It is toxic to humans because it binds to hemoglobin, reducing oxygen transport.

Accepted Answer

It is toxic to humans because it binds to hemoglobin, reducing oxygen transport.

Question 16

Which of the following is the correct order of increasing bond strength for the following types of chemical bonds: metallic, covalent, ionic?
Correct answer: Metallic \u003c Covalent \u003c Ionic

Accepted Answer

Metallic \u003c Covalent \u003c Ionic

Question 17

A student titrates 25.0 cm³ of hydrochloric acid with 0.100 mol/dm³ sodium hydroxide. It takes 30.0 cm³ of NaOH to neutralize the acid. What is the concentration of the hydrochloric acid?
Correct answer: 0.120 mol/dm³

Accepted Answer

0.120 mol/dm³

Question 18

Which of the following best describes the difference between a compound and a mixture?
Correct answer: A compound has a fixed composition, while a mixture does not.

Accepted Answer

A compound has a fixed composition, while a mixture does not.

Question 19

Which of the following is a correct statement about acids, bases, and salts?
Correct answer: A base reacts with an acid to form a salt and water.

Accepted Answer

A base reacts with an acid to form a salt and water.

Question 20

Which of the following best explains why copper does not react with dilute hydrochloric acid?
Correct answer: Copper is less reactive than hydrogen and cannot displace it from the acid.

Accepted Answer

Copper is less reactive than hydrogen and cannot displace it from the acid.

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards