CSEC Chemistry Paper 1 May/June 2026 - Free CXC Past Paper with Answers

'Mass number' is the number of

neutrons plus protons

electrons plus protons

electrons plus neutrons

neutrons minus protons

Which of the following statements is true with regard to protons?

Protons are negatively charged and are found in shells.

Protons are positively charged and are found in the nucleus.

Protons have no charge and are found in the nucleus.

Which of the following terms describes the structure of copper?

Which of the following techniques may be used to separate a mixture of plant pigments?

Fractional distillation

Paper chromatography

The calcium ion has an oxidation number of +2 because the calcium atom has

two electrons in its outermost shell

six electrons in its outermost shell

Item 6 refers to Compound X which melts at 18 °C and boils at 55 °C.

Compound X is MOST likely

In which of the following compounds does hydrogen have a negative oxidation number?

Which of the following mixtures are arranged in order of INCREASING particle size?

Solutions, colloids, suspensions

Solutions, suspensions, colloids

Colloids, solutions, suspensions

Suspensions, colloids, solutions

The rate of a chemical reaction does NOT depend on the

presence of a catalyst

concentration of the reactants

temperature of the reacting system

energy change associated with the reaction

Sodium hydrogen carbonate and hydrochloric acid reacted to produce sodium chloride. The mixture effervesced. The effervescence is caused by the evolution of

In order to prepare a sample of sodium chloride, 3 g of sodium hydrogen carbonate are added to 100 cm³ of 0.2 mol dm⁻³ hydrochloric acid. The number of moles of hydrochloric acid used in this reaction is

$\frac{100 \times 0.2}{1000}$

$\frac{1000 \times 0.2}{100}$

An element, X, has 8 electrons in its outer shell. Which of the following are possible isotopes of X?

Which set of elements forms molecules which contain two atoms?

Which of the following acids is weakly ionized in aqueous solutions?

Which of the following is the correct formula for ammonium carbonate?

(NH₄)₂ (CO₃)₂

Which of the following terms describes calcium chloride?

Giant ionic structure

Giant covalent structure

Simple molecular structure

Macromolecular structure

Item 17 refers to the following graph which shows what occurs when a solution of sodium hydroxide is neutralized by the addition of dilute hydrochloric acid.

Which of the points on the graph represents the neutralization point of the reaction?

Which of the following atoms would NOT form a positive ion?

Which of the following pairs of substances would be MOST suitable for the preparation of copper sulfate crystals?

Copper and dilute sulfuric acid

Copper and concentrated sulfuric acid

Copper nitrate and dilute sulfuric acid

Copper oxide and dilute sulfuric acid

Which of the following ionic equations involves oxidation?

$S^{2-} \rightarrow S + 2e^{-}$

$Na^{+} + e^{-} \rightarrow Na$

$2H^{+} + 2e^{-} \rightarrow H_{2}$

$Cl_{2} + 2e^{-} \rightarrow 2Cl^{-}$

The atomic number of Element D is 13. In which group of the periodic table would Element D be found?

Which of the following statements is true of an endothermic reaction?

Heat is given up to the surroundings.

Heat is absorbed from the surroundings.

The products have less energy than the reactants.

The products have the same energy as the reactants.

Which of the following substances, when added to pure water, SIGNIFICANTLY increases the water's conductivity?

Copper(II) hydroxide

Which of the following aqueous solutions contains 1 mole of hydrogen ions?

2 dm³ of 0.5 mol dm⁻³ HCl

2 dm³ of 0.5 mol dm⁻³ H₂SO₄

1 dm³ of 1.0 mol dm⁻³ H₂SO₄

1 dm³ of 1.0 mol dm⁻³ CH₃COOH

A substance, Y, reacts with an ammonium salt to produce ammonia gas. Y must therefore be

An ion with a single negative charge may be converted into a neutral atom of the same element by

How many coulombs (C) of electricity passes through an electrolyte when a current of 100 A flows for 10 minutes?

The particle $^{24}_{12}X^{2+}$ has 12 protons. How many neutrons and electrons does the particle have?

Neutrons 12 / Electrons 10

Neutrons 12 / Electrons 12

Neutrons 24 / Electrons 10

Neutrons 24 / Electrons 12

Which of the following oxides reacts with both acids and bases?

Item 30 refers to the following table.

The strongest acid is

In which of the following substances will electrolysis NOT occur when an electrical current is passed through it?

Sodium hydroxide solution

Molten sodium chloride

Solid sodium chloride

Dilute sulfuric acid

Barium is below calcium in Group II of the periodic table. When these two metals react with water, the main difference observed is the

colour of the product

colour change with litmus

Which metal reacts vigorously with water to produce a strongly alkaline solution?

Which metal has an alloy which is used in the manufacture of aircraft?

Which of the following methods can be used in the extraction of aluminium?

Displacement by a metal higher up the electrochemical series

Electrolysis of the oxide in its molten state

Reduction of the oxide by hydrogen

Reduction of the oxide by carbon

Which of the following compounds may be used to counteract the effects of acid rain on the soil?

Which of the following metals neither reacts with water nor displaces hydrogen from dilute hydrochloric acid?

Why is aluminium more resistant to corrosion than iron?

Aluminium oxide formed is more reactive than iron oxide formed.

Aluminium has reacted completely but iron has not reacted completely.

Aluminium oxide does not react with aluminium but iron oxide reacts with iron.

Aluminium oxide protects the aluminium but iron oxide does not protect the iron.

Item 39 refers to the following table which shows the reaction of four metals, W, X, Y and Z, with water or steam. The table also shows the products formed when the nitrates of each metal are heated.

Which of the metals is likely to form a soluble hydroxide?

Which of the following elements would NOT form an acidic oxide when burnt in air?

Ammonia may be produced in the laboratory by heating a mixture of ammonium chloride and

Item 42 refers to the following sequence of reactions involving iron compounds, where I, II, III and IV represent progressive stages in the sequence. <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>F</mi><mi>e</mi><mi>C</mi><msub><mi>O</mi><mn>3</mn></msub><mover><mo>→</mo><mi>I</mi></mover><mi>F</mi><mi>e</mi><mi>O</mi><mover><mo>→</mo><mrow><mi>I</mi><mi>I</mi></mrow></mover><mi>F</mi><msub><mi>e</mi><mn>2</mn></msub><msub><mi>O</mi><mn>3</mn></msub><mover><mo>→</mo><mrow><mi>I</mi><mi>I</mi><mi>I</mi></mrow></mover><mi>F</mi><msub><mi>e</mi><mn>2</mn></msub><mo stretchy="false">(</mo><mi>S</mi><msub><mi>O</mi><mn>4</mn></msub><msub><mo stretchy="false">)</mo><mn>3</mn></msub><mover><mo>→</mo><mrow><mi>I</mi><mi>V</mi></mrow></mover><mi>F</mi><mi>e</mi><mo stretchy="false">(</mo><mi>O</mi><mi>H</mi><msub><mo stretchy="false">)</mo><mn>3</mn></msub></math>

A suitable reagent that could be used at Stage IV is

aqueous sodium hydroxide

Which of the following metals appears between copper and aluminium in the reactivity series and is an important component in haemoglobin?

Item 44 refers to the following information. When treated with concentrated hydrochloric acid, a compound gives off a greenish-yellow gas which bleaches moist red litmus paper.

The gas given off is

How many covalent bonds are there in a nitrogen molecule?

Item 46 refers to the following information.

A solution of iron(II) sulfate was added to a solution of barium nitrate until in EXCESS. The precipitate produced was filtered off and water was added to the residue in the filter paper.

The colour of the precipitate produced was

Item 47 refers to the following diagram of the fully displayed formula of a compound.

H H O | | || H-C-C-C | | H H O-H

To which homologous series does the compound belong ?

When a hydrocarbon molecule is cracked, which of the following smaller molecules are produced?

I. An alkane II. An alkene III. An alcohol

The compound 2-bromobutane has a structural formula of

Which of the following molecular formulae represents the alcohol whose boiling point is 160 °C?

The forward reaction is known as

Cellulose is an example of a polysaccharide that can be used for the manufacture of

Which of the following reactions occurs between propene and bromine?

Which of the following statements is true of soapless detergents?

They are made from fats.

They are all biodegradable.

They are inorganic materials.

They are not affected by hard water.

What is the name of the process by which proteins are formed from amino acids?

Which of the following compounds can decolourize potassium manganate(VII)?

Octane, the major component of gasoline, is an alkane with eight carbon atoms per molecule. Which of the following formulae represents octane?

Which of the following is NOT formed from condensation polymerization?

Which reaction involves the boiling of a fat or oil with aqueous sodium hydroxide (caustic soda)?

Which of the following organic molecules has only two structural isomers?

CSEC Chemistry Paper 1 May/June 2026 - Free CXC Past Paper with Answers

CSEC Chemistry Paper 1 May/June 2026 Questions