Question 1

A student is tasked with separating a mixture of sand, salt, and iron filings. Which sequence of experimental techniques would most effectively separate all three components?

Accepted Answer

Use a magnet to remove iron filings, dissolve the mixture in water to dissolve salt, then filter to separate sand.

Question 2

Which of the following best explains why water is considered a compound and not a mixture?

Accepted Answer

Water consists of two elements chemically combined in a fixed ratio.

Question 3

A chemical reaction is observed to release heat and cause the temperature of the surroundings to rise. Which term best describes this reaction, and what is the sign of its enthalpy change (ΔH)?

Accepted Answer

Exothermic; ΔH is negative

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 5

A student is asked to balance the following equation: __Al + __O2 → __Al2O3. What are the correct coefficients for Al, O2, and Al2O3, respectively?

Accepted Answer

4, 3, 2

Question 6

During the electrolysis of molten sodium chloride (NaCl), which products are formed at the cathode and anode, respectively?

Accepted Answer

Sodium at the cathode, chlorine at the anode

Question 7

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?

Accepted Answer

Reactivity increases because outer electrons are more easily lost.

Question 8

A solution has a pH of 2. Which of the following statements is correct about this solution?

Accepted Answer

It is a strong acid.

Question 9

Which of the following is a correct application of green chemistry principles in industry?

Accepted Answer

Using renewable raw materials to manufacture plastics.

Question 10

A hydrocarbon undergoes complete combustion in excess oxygen. Which products are always formed?

Accepted Answer

Carbon dioxide and water

Question 11

A student titrates 25.0 cm³ of hydrochloric acid (HCl) with sodium hydroxide (NaOH) of known concentration. Which piece of apparatus should be used to accurately measure the volume of NaOH added?

Accepted Answer

Burette

Question 12

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

They have free-moving delocalized electrons.

Question 13

A sample of calcium carbonate (CaCO3) is heated strongly. Which type of chemical reaction occurs, and what are the products?

Accepted Answer

Decomposition; calcium oxide and carbon dioxide

Question 14

Which of the following is a limitation of the scientific method in chemistry?

Accepted Answer

It may not always provide a definitive answer due to limitations in measurement and observation.

Question 15

A chemist needs to calculate the number of moles in 18 grams of water (H2O). What is the correct calculation?

Accepted Answer

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

Question 16

Which of the following best describes the process of water treatment for safe drinking water?

Accepted Answer

Filtration and chlorination to remove impurities and kill bacteria.

Question 17

Which statement about the rates of chemical reactions is correct?

Accepted Answer

Increasing temperature generally increases the rate of reaction.

Question 18

Which of the following is an example of a redox reaction?

Accepted Answer

The reaction between zinc and copper(II) sulfate solution.

Question 19

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound has components chemically combined in fixed ratios, while a mixture has components physically combined in variable ratios.

Question 20

Which of the following is a correct example of applying chemistry to benefit the environment?

Accepted Answer

Developing biodegradable plastics to reduce landfill waste.

Cambridge IGCSE Chemistry 0620: Syllabus Overview and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards