Question 1

A student is investigating the change of state from solid to gas without passing through the liquid phase. Which process is the student observing, and which real-world example best illustrates this phenomenon?

Accepted Answer

Sublimation; dry ice disappearing at room temperature

Question 2

Which statement best explains why water (H₂O) is classified as a compound and not an element?

Accepted Answer

It consists of two different elements chemically bonded together

Question 3

A chemist reacts 16 g of oxygen (O₂) with hydrogen to form water (H₂O). Given the molar mass of O₂ is 32 g/mol and H₂O is 18 g/mol, what mass of water is produced, assuming complete reaction and excess hydrogen? (Use the balanced equation: 2H₂ + O₂ → 2H₂O)

Accepted Answer

36 g

Question 4

During the electrolysis of water, which statement correctly describes what happens at the cathode?

Accepted Answer

Hydrogen gas is produced by reduction

Question 5

A chemical cold pack used in sports injuries absorbs heat from its surroundings when activated. Which type of reaction is occurring, and what is the sign of ΔH for this process?

Accepted Answer

Endothermic; ΔH is positive

Question 6

Which of the following is an example of a displacement reaction, and what is the main characteristic of this type of reaction?

Accepted Answer

Zn + CuSO₄ → ZnSO₄ + Cu; a more reactive element replaces a less reactive one

Question 7

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

Accepted Answer

It is acidic and contains a high concentration of H⁺ ions

Question 8

Which trend is observed as you move down Group 1 (alkali metals) in the Periodic Table?

Accepted Answer

Reactivity increases and melting point decreases

Question 9

Iron is extracted from its ore in a blast furnace. Which property of iron makes it suitable for use in construction?

Accepted Answer

It is malleable and strong

Question 10

Catalytic converters in cars help reduce environmental pollution. Which gases are primarily targeted by catalytic converters, and what is the main chemical process involved?

Accepted Answer

Nitrogen oxides and carbon monoxide; redox reactions

Question 11

Which of the following compounds is classified as an alcohol, and what functional group does it contain?

Accepted Answer

C₂H₅OH; contains a hydroxyl (-OH) group

Question 12

A student uses titration to determine the concentration of hydrochloric acid (HCl) in a solution. Which of the following best describes the role of the indicator in this experiment?

Accepted Answer

It changes color at the endpoint to signal neutralization

Question 13

Which statement best describes the law of conservation of mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants equals the total mass of products

Question 14

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

Accepted Answer

They have loosely held electrons that can move freely

Question 15

A student is asked to identify an unknown colorless solution. Which experimental technique would be most appropriate for determining the presence of different ions in the solution?

Accepted Answer

Chemical analysis using specific reagents

Question 16

Which of the following is a correct statement about the arrangement of elements in the Periodic Table?

Accepted Answer

Elements are arranged in order of increasing atomic number

Question 17

Which of the following best describes the main safety precaution when heating a substance in a test tube during a laboratory experiment?

Accepted Answer

Point the open end of the test tube away from yourself and others

Question 18

Which of the following is a real-world application of stoichiometry in the medical field?

Accepted Answer

Calculating the correct dosage of a drug based on patient mass and molar mass

Question 19

Which of the following statements about organic compounds is correct?

Accepted Answer

Organic compounds are based on carbon atoms bonded to other elements

Question 20

A student observes that a chemical reaction produces a temperature increase in the surroundings. Which type of reaction is this, and what is a common real-life example?

Accepted Answer

Exothermic; combustion of natural gas in a stove

Cambridge IGCSE Chemistry 0620: Syllabus Overview and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards