Question 1

A student is given a sample of a white crystalline solid. To determine whether it is sodium chloride or sugar, which experimental technique would be most appropriate?
Correct answer: Dissolve the solid in water and test the conductivity of the solution.

Accepted Answer

Dissolve the solid in water and test the conductivity of the solution.

Question 2

Which of the following best explains why graphite conducts electricity but diamond does not?
Correct answer: Graphite contains delocalized electrons that can move between layers.

Accepted Answer

Graphite contains delocalized electrons that can move between layers.

Question 3

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

Accepted Answer

35.5

Question 4

Which of the following statements about ionic and covalent compounds is correct?
Correct answer: Ionic compounds conduct electricity when molten, while covalent compounds generally do not.

Accepted Answer

Ionic compounds conduct electricity when molten, while covalent compounds generally do not.

Question 5

A student is asked to prepare a pure, dry sample of copper(II) sulfate crystals from copper(II) oxide and dilute sulfuric acid. Which sequence of steps is correct?
Correct answer: Add excess copper(II) oxide to sulfuric acid, filter, and evaporate the filtrate.

Accepted Answer

Add excess copper(II) oxide to sulfuric acid, filter, and evaporate the filtrate.

Question 6

Which of the following best describes the environmental impact of burning fossil fuels?
Correct answer: It releases carbon dioxide, contributing to global warming.

Accepted Answer

It releases carbon dioxide, contributing to global warming.

Question 7

A solution of hydrochloric acid is titrated with sodium hydroxide. Which indicator would be most suitable for this reaction, and why?
Correct answer: Methyl orange, because it changes color in the acidic to neutral pH range.

Accepted Answer

Methyl orange, because it changes color in the acidic to neutral pH range.

Question 8

Which of the following is a correct statement about the arrangement of elements in the Periodic Table?
Correct answer: Elements are arranged in order of increasing atomic number.

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 9

A student mixes 25.0 g of calcium carbonate with 50.0 g of hydrochloric acid. The reaction produces calcium chloride, water, and carbon dioxide. If the theoretical yield of carbon dioxide is 11.0 g, but only 9.5 g is collected, what is the percentage yield?
Correct answer: 86.4%

Accepted Answer

86.4%

Question 10

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 11

During an experiment, a student observes that a reaction mixture becomes colder as the reaction proceeds. Which type of reaction is this, and what is the energy change involved?
Correct answer: Endothermic; energy is absorbed from the surroundings.

Accepted Answer

Endothermic; energy is absorbed from the surroundings.

Question 12

Which of the following is a correct description of an isotope?
Correct answer: Atoms of the same element with different numbers of neutrons.

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 13

A student is asked to identify an unknown gas that turns damp red litmus paper blue. Which gas is most likely present?
Correct answer: Ammonia

Accepted Answer

Ammonia

Question 14

Which of the following best describes the process of electrolysis?
Correct answer: The decomposition of a compound using electricity.

Accepted Answer

The decomposition of a compound using electricity.

Question 15

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 16

Which of the following is the best method to separate a mixture of sand and salt?
Correct answer: Dissolve the mixture in water, filter, and evaporate the filtrate.

Accepted Answer

Dissolve the mixture in water, filter, and evaporate the filtrate.

Question 17

Which of the following is a property of giant covalent structures like diamond?
Correct answer: They have very high melting points due to strong covalent bonds throughout the structure.

Accepted Answer

They have very high melting points due to strong covalent bonds throughout the structure.

Question 18

A student is given a hydrocarbon and asked to determine if it is saturated or unsaturated. Which test should be performed?
Correct answer: Add bromine water and observe if the color disappears.

Accepted Answer

Add bromine water and observe if the color disappears.

Question 19

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 20

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

Cambridge IGCSE Chemistry 0620 Syllabus Overview and Key Concepts

Study Guide - Practice Questions

Study Guide - Flashcards