Question 1

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

Accepted Answer

Metals have loosely bound electrons that can move freely throughout the structure.

Question 2

A sample of calcium carbonate (CaCO₃) is heated strongly and decomposes according to the equation: CaCO₃(s) → CaO(s) + CO₂(g). If 10.0 g of CaCO₃ is decomposed, what is the maximum mass of CaO that can be formed? (Relative atomic masses: Ca = 40, C = 12, O = 16)
Correct answer: 5.6 g

Accepted Answer

5.6 g

Question 3

Which of the following statements about acids, bases, and salts is correct?
Correct answer: An acid is a substance that donates protons (H⁺ ions) in solution.

Accepted Answer

An acid is a substance that donates protons (H⁺ ions) in solution.

Question 4

A student is given a mixture of sand and sodium chloride (table salt). Which sequence of experimental techniques would best separate and recover both substances?
Correct answer: Dissolve in water, filter, evaporate the filtrate.

Accepted Answer

Dissolve in water, filter, evaporate the filtrate.

Question 5

Which of the following best describes the environmental impact of excessive use of nitrogen-based fertilizers?
Correct answer: They cause eutrophication in water bodies, leading to algal blooms.

Accepted Answer

They cause eutrophication in water bodies, leading to algal blooms.

Question 6

Which of the following is the correct electron configuration for a neutral atom of sodium (Na, atomic number 11)?
Correct answer: 1s² 2s² 2p⁶ 3s¹

Accepted Answer

1s² 2s² 2p⁶ 3s¹

Question 7

A solution contains 0.5 moles of solute dissolved in 2.0 dm³ of solution. What is the concentration of the solution in mol/dm³?
Correct answer: 0.25 mol/dm³

Accepted Answer

0.25 mol/dm³

Question 8

Which of the following best explains why diamond is much harder than graphite, even though both are forms of carbon?
Correct answer: Diamond has a giant covalent structure with each carbon atom bonded to four others, while graphite has layers held together by weak forces.

Accepted Answer

Diamond has a giant covalent structure with each carbon atom bonded to four others, while graphite has layers held together by weak forces.

Question 9

During electrolysis of molten sodium chloride, which products are formed at the cathode and anode, respectively?
Correct answer: Sodium at the cathode, chlorine at the anode

Accepted Answer

Sodium at the cathode, chlorine at the anode

Question 10

A chemical reaction is exothermic if:
Correct answer: Energy is released to the surroundings.

Accepted Answer

Energy is released to the surroundings.

Question 11

Which of the following best describes the trend in reactivity of Group 1 elements (alkali metals) as you move down the group in the Periodic Table?
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 12

Which of the following is a correct example of a redox reaction?
Correct answer: Zinc metal reacts with copper(II) sulfate to produce zinc sulfate and copper.

Accepted Answer

Zinc metal reacts with copper(II) sulfate to produce zinc sulfate and copper.

Question 13

A student is asked to calculate the number of moles in 18 g of water (H₂O). (Relative atomic masses: H = 1, O = 16)
Correct answer: 1 mole

Accepted Answer

1 mole

Question 14

Which of the following is the best reason for using a fume hood when working with concentrated hydrochloric acid in the laboratory?
Correct answer: To avoid inhaling harmful vapors.

Accepted Answer

To avoid inhaling harmful vapors.

Question 15

Which of the following best describes the process of fractional distillation?
Correct answer: It separates liquids with different boiling points by repeated vaporization and condensation.

Accepted Answer

It separates liquids with different boiling points by repeated vaporization and condensation.

Question 16

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 17

A student mixes 25.0 cm³ of 2.00 mol/dm³ hydrochloric acid with 25.0 cm³ of 2.00 mol/dm³ sodium hydroxide. What is the concentration of sodium chloride formed, assuming total volume is additive and reaction goes to completion?
Correct answer: 1.00 mol/dm³

Accepted Answer

1.00 mol/dm³

Question 18

Which of the following best explains why carbon monoxide (CO) is considered a pollutant in the environment?
Correct answer: It binds to hemoglobin in blood, reducing oxygen transport.

Accepted Answer

It binds to hemoglobin in blood, reducing oxygen transport.

Overview of Cambridge IGCSE Chemistry 0620 Syllabus

Study Guide - Practice Questions

Study Guide - Flashcards