Question 1

A sample of chlorine gas contains two isotopes: 75% 35Cl (atomic mass = 34.97 u) and 25% 37Cl (atomic mass = 36.97 u). What is the relative atomic mass of chlorine in this sample?
Correct answer: 35.50 u

Accepted Answer

35.50 u

Question 2

Which of the following best explains why sodium chloride conducts electricity when molten but not when solid?
Correct answer: The ions are free to move in the molten state but fixed in the solid state.

Accepted Answer

The ions are free to move in the molten state but fixed in the solid state.

Question 3

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

Accepted Answer

Dissolve in water, filter, evaporate water from filtrate

Question 4

Which of the following statements about Group 1 elements in the Periodic Table is correct?
Correct answer: They have one electron in their outermost shell.

Accepted Answer

They have one electron in their outermost shell.

Question 5

A reaction is carried out in a closed container: 2H2(g) + O2(g) → 2H2O(l). Which statement best describes the energy changes in this reaction?
Correct answer: It is exothermic because energy is released when bonds form in water.

Accepted Answer

It is exothermic because energy is released when bonds form in water.

Question 6

Which of the following best describes the difference between ionic and covalent bonding?
Correct answer: Ionic bonding involves the transfer of electrons; covalent bonding involves the sharing of electrons.

Accepted Answer

Ionic bonding involves the transfer of electrons; covalent bonding involves the sharing of electrons.

Question 7

A 0.25 mol sample of magnesium reacts completely with hydrochloric acid. How many moles of HCl are required? (Mg + 2HCl → MgCl2 + H2)
Correct answer: 0.50 mol

Accepted Answer

0.50 mol

Question 8

Which of the following is a correct statement about the kinetic particle theory as it applies to gases?
Correct answer: Gas particles move randomly and rapidly, with negligible forces between them.

Accepted Answer

Gas particles move randomly and rapidly, with negligible forces between them.

Question 9

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

Accepted Answer

Concentration of reactants

Question 10

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

Accepted Answer

They have delocalized electrons that move freely throughout the structure.

Question 11

A solution of hydrochloric acid is titrated with sodium hydroxide. Which indicator would be most suitable for this titration?
Correct answer: Methyl orange

Accepted Answer

Methyl orange

Question 12

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

Accepted Answer

4Al + 3O2 → 2Al2O3

Question 13

Which of the following environmental issues is most directly related to the combustion of fossil fuels?
Correct answer: Acid rain formation

Accepted Answer

Acid rain formation

Question 14

Which of the following statements about isotopes is correct?
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 15

Which of the following best describes the trend in reactivity of the halogens (Group 17) as you go down the group?
Correct answer: Reactivity decreases down the group.

Accepted Answer

Reactivity decreases down the group.

Question 16

A hydrocarbon burns in excess oxygen to form carbon dioxide and water. Which type of reaction is this?
Correct answer: Combustion

Accepted Answer

Combustion

Question 17

Which of the following is the best method to obtain pure copper(II) sulfate crystals from a solution?
Correct answer: Crystallization

Accepted Answer

Crystallization

Question 18

A student electrolyzes aqueous 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 19

Which of the following best explains why diamond is hard and has a high melting point?
Correct answer: Each carbon atom forms four strong covalent bonds in a giant lattice.

Accepted Answer

Each carbon atom forms four strong covalent bonds in a giant lattice.

Question 20

A student calculates the empirical formula of a compound containing 40% sulfur and 60% oxygen by mass. What is the empirical formula? (S = 32, O = 16)
Correct answer: SO2

Accepted Answer

SO2

Overview and Key Concepts of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards