Question 1

A student is asked to separate a mixture of sand, salt, and iron filings. Which sequence of experimental techniques would best achieve this separation?
Correct answer: Add water, filter, use a magnet, evaporate the filtrate

Accepted Answer

Add water, filter, use a magnet, evaporate the filtrate

Question 2

Which of the following statements best explains why diamond is used in cutting tools, while graphite is used as a lubricant?
Correct answer: Diamond has a giant covalent structure with strong bonds in all directions, making it hard; graphite has layers that slide over each other due to weak forces between them.

Accepted Answer

Diamond has a giant covalent structure with strong bonds in all directions, making it hard; graphite has layers that slide over each other due to weak forces between them.

Question 3

A sample of chlorine contains two isotopes: 75% Cl-35 and 25% Cl-37. What is the relative atomic mass of chlorine to two decimal places?
Correct answer: undefined

Accepted Answer

Question 4

Which of the following best describes the process of electrolysis in the extraction of aluminum from its ore?
Correct answer: Aluminum oxide is dissolved in molten cryolite and electricity is passed through the solution, causing aluminum ions to gain electrons at the cathode.

Accepted Answer

Aluminum oxide is dissolved in molten cryolite and electricity is passed through the solution, causing aluminum ions to gain electrons at the cathode.

Question 5

Which of the following reactions is an example of a redox reaction?
Correct answer: Zinc + Copper(II) sulfate → Zinc sulfate + Copper

Accepted Answer

Zinc + Copper(II) sulfate → Zinc sulfate + Copper

Question 6

A student is asked to prepare a pure, dry sample of copper(II) sulfate crystals from copper(II) oxide and sulfuric acid. Which steps should they follow?
Correct answer: Add copper(II) oxide to warm sulfuric acid until in excess, filter, and evaporate the filtrate to crystallization.

Accepted Answer

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

Question 7

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

Accepted Answer

They have a full outer shell of electrons, making them stable.

Question 8

A student measures the temperature change when hydrochloric acid reacts with sodium hydroxide. The temperature increases. What type of reaction is this, and what does it indicate about the enthalpy change?
Correct answer: Exothermic; the enthalpy change is negative

Accepted Answer

Exothermic; the enthalpy change is negative

Question 9

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 10

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

Accepted Answer

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

Question 11

A chemical plant releases sulfur dioxide into the atmosphere. Which environmental problem is most directly caused by this emission?
Correct answer: Acid rain

Accepted Answer

Acid rain

Question 12

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, increasing the reaction rate.

Accepted Answer

It provides an alternative pathway with lower activation energy, increasing the reaction rate.

Question 13

A student is given a colorless solution and asked to identify the presence of chloride ions. Which reagent should they use, and what observation would confirm the presence of chloride ions?
Correct answer: Add silver nitrate; a white precipitate forms

Accepted Answer

Add silver nitrate; a white precipitate forms

Question 14

Which of the following best explains why water is a good solvent for ionic compounds?
Correct answer: Water molecules are polar and can surround and separate the ions.

Accepted Answer

Water molecules are polar and can surround and separate the ions.

Question 15

Which of the following is the correct balanced equation for the reaction between magnesium and hydrochloric acid?
Correct answer: Mg + 2HCl → MgCl2 + H2

Accepted Answer

Mg + 2HCl → MgCl2 + H2

Question 16

A hydrocarbon burns in excess oxygen to form carbon dioxide and water. What type of reaction is this, and what is the general formula for the hydrocarbon if it is an alkane?
Correct answer: Combustion; CnH2n+2

Accepted Answer

Combustion; CnH2n+2

Question 17

Which of the following best describes the difference between an element and a compound?
Correct answer: An element consists of only one type of atom, while a compound contains two or more different elements chemically combined.

Accepted Answer

An element consists of only one type of atom, while a compound contains two or more different elements chemically combined.

Question 18

A student is asked to calculate the percentage by mass of oxygen in calcium carbonate (CaCO3). (Ca = 40, C = 12, O = 16)
Correct answer: 48%

Accepted Answer

48%

Question 19

Which of the following best explains why metals are malleable and conduct electricity?
Correct answer: Metals have a lattice of positive ions surrounded by a sea of delocalized electrons.

Accepted Answer

Metals have a lattice of positive ions surrounded by a sea of delocalized electrons.

Question 20

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.

Overview and Key Concepts of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards