Question 1

A sealed syringe contains a fixed amount of gas at room temperature. If the syringe is placed in a hot water bath, which of the following best describes what happens to the pressure inside the syringe, assuming the volume is kept constant?
Correct answer: The pressure increases because the gas particles move faster and collide with the walls more frequently.

Accepted Answer

The pressure increases because the gas particles move faster and collide with the walls more frequently.

Question 2

Which of the following best explains why graphite can conduct electricity, but diamond cannot?
Correct answer: Graphite has delocalized electrons that can move between layers, while diamond does not.

Accepted Answer

Graphite has delocalized electrons that can move between layers, while diamond does not.

Question 3

A student is asked to determine the relative atomic mass (Ar) of chlorine using the following data: 75% of chlorine atoms have a mass of 35, and 25% have a mass of 37. What is the correct value for Ar(Cl)?
Correct answer: 35.5

Accepted Answer

35.5

Question 4

Which of the following is the best 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 5

A student is planning an experiment to investigate the effect of concentration on the rate of a chemical reaction. Which variable should be kept constant to ensure a fair test?
Correct answer: Temperature of the reaction mixture.

Accepted Answer

Temperature of the reaction mixture.

Question 6

Which of the following statements about ionic compounds is correct?
Correct answer: They conduct electricity when molten because ions are free to move.

Accepted Answer

They conduct electricity when molten because ions are free to move.

Question 7

A sample of gas is compressed at constant temperature. What happens to the average distance between the gas particles and why?
Correct answer: The average distance decreases because the particles are forced closer together.

Accepted Answer

The average distance decreases because the particles are forced closer together.

Question 8

Which of the following best describes the role of a salt bridge in an electrochemical cell?
Correct answer: It allows ions to move between the two half-cells to maintain electrical neutrality.

Accepted Answer

It allows ions to move between the two half-cells to maintain electrical neutrality.

Question 9

A student is asked to identify an unknown metal by reacting it with dilute hydrochloric acid and measuring the temperature change. Which type of chemical reaction is being investigated?
Correct answer: Exothermic reaction, because heat is released when the metal reacts with acid.

Accepted Answer

Exothermic reaction, because heat is released when the metal reacts with acid.

Question 10

Which of the following is a correct statement about isotopes?
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 11

Which of the following best explains why metals are malleable?
Correct answer: The layers of positive ions can slide over each other while the delocalized electrons maintain the metallic bond.

Accepted Answer

The layers of positive ions can slide over each other while the delocalized electrons maintain the metallic bond.

Question 12

A student is given a mixture of sand and salt. Which sequence of experimental techniques would best separate and purify both components?
Correct answer: Dissolve in water, filter, evaporate water from filtrate.

Accepted Answer

Dissolve in water, filter, evaporate water from filtrate.

Question 13

Which of the following is a correct description of 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 14

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 15

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? (Ar: S = 32, O = 16)
Correct answer: SO3

Accepted Answer

SO3

Question 16

Which of the following is a correct statement about acids and bases?
Correct answer: Acids release hydrogen ions (H+) in aqueous solution, while bases release hydroxide ions (OH-).

Accepted Answer

Acids release hydrogen ions (H+) in aqueous solution, while bases release hydroxide ions (OH-).

Question 17

Which of the following best describes the trend in reactivity of Group 1 metals as you go down the group?
Correct answer: Reactivity increases because the outer electron is further from the nucleus and more easily lost.

Accepted Answer

Reactivity increases because the outer electron is further from the nucleus and more easily lost.

Question 18

A student is asked to evaluate the method used in a titration experiment. Which of the following would be the best suggestion for improving the accuracy of the results?
Correct answer: Repeat the titration several times and calculate an average.

Accepted Answer

Repeat the titration several times and calculate an average.

Question 19

Which of the following is a correct statement about the use of chemical equations in stoichiometry?
Correct answer: Balanced chemical equations show the mole ratios of reactants and products.

Accepted Answer

Balanced chemical equations show the mole ratios of reactants and products.

Question 20

Which of the following is the best reason for using a fume hood when working with volatile organic solvents in the laboratory?
Correct answer: To prevent inhalation of harmful vapors and ensure safe laboratory practice.

Accepted Answer

To prevent inhalation of harmful vapors and ensure safe laboratory practice.

Overview and Key Concepts of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards