Question 1

A student is given a sample of an unknown white powder. Which experimental technique would be most appropriate to determine if the powder is a pure substance or a mixture?
Correct answer: Measuring its melting point and comparing it to a known value

Accepted Answer

Measuring its melting point and comparing it to a known value

Question 2

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 3

A 12.0 g sample of magnesium (Mg, molar mass = 24.3 g/mol) reacts completely with oxygen. How many moles of magnesium are present in the sample?
Correct answer: 0.494 mol

Accepted Answer

0.494 mol

Question 4

Which of the following is a correct statement about acids, bases, and salts?
Correct answer: A salt is formed when an acid reacts with a base in a neutralization reaction

Accepted Answer

A salt is formed when an acid reacts with a base in a neutralization reaction

Question 5

During electrolysis of molten sodium chloride, which product is formed at the cathode?
Correct answer: Sodium metal

Accepted Answer

Sodium metal

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 student mixes hydrochloric acid (HCl) with sodium hydroxide (NaOH) in a beaker. The temperature of the solution increases. What type of reaction is this, and what does the temperature change indicate?
Correct answer: Exothermic neutralization; energy is released to the surroundings

Accepted Answer

Exothermic neutralization; energy is released to the surroundings

Question 8

Which of the following statements about the Periodic Table is correct?
Correct answer: Elements in the same group have similar chemical properties

Accepted Answer

Elements in the same group have similar chemical properties

Question 9

A solution contains 0.5 mol of NaCl dissolved in 250 cm³ of water. What is the concentration of NaCl in mol/dm³?
Correct answer: 2.0 mol/dm³

Accepted Answer

2.0 mol/dm³

Question 10

Which of the following is an example of a chemical change?
Correct answer: Iron rusting when exposed to air

Accepted Answer

Iron rusting when exposed to air

Question 11

Which statement best explains why ionic compounds have high melting points?
Correct answer: Strong electrostatic forces hold the ions together in a lattice

Accepted Answer

Strong electrostatic forces hold the ions together in a lattice

Question 12

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, then evaporate the filtrate

Accepted Answer

Dissolve in water, filter, then evaporate the filtrate

Question 13

Which of the following best describes the role of a catalyst in a chemical reaction?
Correct answer: It lowers the activation energy, increasing the reaction rate

Accepted Answer

It lowers the activation energy, increasing the reaction rate

Question 14

Which of the following is a correct balanced equation for the reaction between sulfuric acid and sodium hydroxide?
Correct answer: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

Accepted Answer

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

Question 15

Which of the following organic compounds is most likely to undergo combustion to produce carbon dioxide and water?
Correct answer: Ethanol (C₂H₅OH)

Accepted Answer

Ethanol (C₂H₅OH)

Question 16

A student is asked to calculate the number of moles in 18 g of water (H₂O, molar mass = 18 g/mol). Which calculation is correct?
Correct answer: n = 18 g / 18 g/mol = 1 mol

Accepted Answer

n = 18 g / 18 g/mol = 1 mol

Question 17

Which of the following best describes a redox reaction?
Correct answer: A reaction in which one substance is oxidized and another is reduced

Accepted Answer

A reaction in which one substance is oxidized and another is reduced

Question 18

Which of the following is a safe laboratory practice?
Correct answer: Wearing safety goggles when handling chemicals

Accepted Answer

Wearing safety goggles when handling chemicals

Question 19

Which of the following best explains why carbon is essential in organic chemistry?
Correct answer: It can form four covalent bonds, allowing for a variety of stable compounds

Accepted Answer

It can form four covalent bonds, allowing for a variety of stable compounds

Question 20

A chemical plant wants to minimize waste and environmental impact. Which approach best aligns with green chemistry principles?
Correct answer: Designing processes that use renewable resources and produce fewer hazardous byproducts

Accepted Answer

Designing processes that use renewable resources and produce fewer hazardous byproducts

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards