Question 1

A sealed syringe contains a fixed amount of gas at room temperature. If the syringe is placed in a freezer, which of the following best describes what happens to the gas inside, according to the kinetic theory of matter?
Correct answer: The gas particles move slower and the pressure decreases.

Accepted Answer

The gas particles move slower and the pressure decreases.

Question 2

Which statement best explains why graphite can conduct electricity but diamond cannot, even though both are forms of carbon?
Correct answer: Graphite has delocalized electrons that can move between layers, while diamond's electrons are all involved in covalent bonds.

Accepted Answer

Graphite has delocalized electrons that can move between layers, while diamond's electrons are all involved in covalent bonds.

Question 3

A student is asked to calculate the relative atomic mass (A_r) of chlorine, given that it consists of 75% chlorine-35 and 25% chlorine-37. Which calculation is correct?
Correct answer: A_r = (0.75 × 35) + (0.25 × 37) = 35.5

Accepted Answer

A_r = (0.75 × 35) + (0.25 × 37) = 35.5

Question 4

Which of the following best describes the process of dissolving table salt (NaCl) in water?
Correct answer: Ionic bonds in NaCl are broken and the ions are surrounded by water molecules.

Accepted Answer

Ionic bonds in NaCl are broken and the ions are surrounded by water molecules.

Question 5

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

Accepted Answer

Add water, filter to separate sand, then evaporate water to recover salt.

Question 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

A chemical reaction is carried out in a closed system and the temperature of the surroundings increases. What can be concluded about the reaction?
Correct answer: The reaction is exothermic because it releases heat to the surroundings.

Accepted Answer

The reaction is exothermic because it releases heat to the surroundings.

Question 9

Which of the following is a property of ionic compounds in the solid state?
Correct answer: They do not conduct electricity because the ions are fixed in place.

Accepted Answer

They do not conduct electricity because the ions are fixed in place.

Question 10

A student is asked to identify an unknown solution as either an acid, a base, or neutral. Which experimental technique would provide the most direct evidence?
Correct answer: Test the solution with universal indicator paper and observe the color change.

Accepted Answer

Test the solution with universal indicator paper and observe the color change.

Question 11

Which of the following best describes the arrangement of electrons in a sodium atom (atomic number 11)?
Correct answer: 2 electrons in the first shell, 8 in the second, 1 in the third

Accepted Answer

2 electrons in the first shell, 8 in the second, 1 in the third

Question 12

Which of the following is a real-world example of a chemical change?
Correct answer: Iron rusting when left outside in the rain

Accepted Answer

Iron rusting when left outside in the rain

Question 13

A student is planning an experiment to determine the effect of temperature on the rate of a chemical reaction. Which variable should be kept constant to ensure a fair test?
Correct answer: Concentration of reactants

Accepted Answer

Concentration of reactants

Question 14

Which of the following best explains why noble gases are unreactive?
Correct answer: They have full outer electron shells, making them stable.

Accepted Answer

They have full outer electron shells, making them stable.

Question 15

Which of the following is a correct statement about 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 16

A student electrolyzes a solution of copper(II) sulfate using copper electrodes. What is observed at the cathode?
Correct answer: Copper metal is deposited.

Accepted Answer

Copper metal is deposited.

Question 17

Which of the following best describes a covalent bond?
Correct answer: A shared pair of electrons between two non-metal atoms.

Accepted Answer

A shared pair of electrons between two non-metal atoms.

Question 18

Which of the following is a correct example of a giant covalent structure and its use?
Correct answer: Diamond, used in cutting tools due to its hardness.

Accepted Answer

Diamond, used in cutting tools due to its hardness.

Question 19

A student is given a sample of an unknown metal. Which property would best help identify it as a metal?
Correct answer: It is malleable and conducts electricity.

Accepted Answer

It is malleable and conducts electricity.

Question 20

Which of the following best describes the role of chemistry in society?
Correct answer: Chemistry helps develop new materials, medicines, and solutions to environmental problems.

Accepted Answer

Chemistry helps develop new materials, medicines, and solutions to environmental problems.

Cambridge IGCSE Chemistry 0620: Syllabus Overview and Key Concepts

Study Guide - Practice Questions

Study Guide - Flashcards