CSEC Chemistry Paper 1 January 2025 - Free CXC Past Paper with Answers

The particles in a solid are arranged

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

Fractional distillation

Paper chromatography

Which of the following elements has seven electrons in its outer shell?

Compounds are formed by

a chemical combination of two or more elements

a chemical combination of only two elements

a mixture of two or more elements

a mixture of only two elements

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

In the notation $^{24}_{12}\text{Mg}$ , the number $12$ represents the

Which of the following substances does NOT conduct electricity?

The bond between the two carbon atoms is

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

Which of the following pairs of elements are isotopes?

Diamond and graphite are allotropes of carbon because

they are the same physical forms of different elements

they are different physical forms of the same element

they both have the same molecular formulae but different structural formulae

they both have different molecular formulae but the same structural formula

Which of the following is NOT a way in which radioactive isotopes are used?

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

Which of the substances, represented by the options A, B, C and D, is MOST likely sodium chloride?

The mass number of an element is the number of

neutrons in an atom of the element

protons and electrons in an atom of the element

neutrons and protons in an atom of the element

protons, neutrons and electrons in an atom of the element

Which of the following occurs during an exothermic reaction?

The energy absorbed when new bonds are formed is less than the energy taken in when breaking the existing bonds.

The energy released when new bonds are formed is equal to the energy taken in when breaking the existing bonds.

The energy absorbed when new bonds are formed is greater than the energy taken in when breaking the existing bonds.

The energy released when new bonds are formed is greater than the energy taken in when breaking the existing bonds.

Which of the following is the correct formula for calcium phosphate?

$\text{Ca}(\text{PO}_4)_2$

$\text{Ca}_3(\text{PO}_4)_2$

$\text{Ca}_2(\text{PO}_4)_3$

An acid may be defined as a

The mass of one mole of atoms of an element refers to the quantity of

one atom of the element

an element which contains $6.0 \times 10^{23}$ atoms

an element which occupies $24.0 \text{ dm}^3$ at STP

an element which combines completely with $12 \text{ g}$ of carbon-12

Metallic bonding is BEST described as

strong forces of attraction between the positive nuclear metal centre and the 'sea of delocalized electrons'

weak forces of attraction between the positive nuclear metal centre and the 'sea of delocalized electrons'

strong forces of attraction between the neutral nuclear centre and the 'sea of delocalized electrons'

weak forces of attraction between the neutral nuclear centre and the 'sea of delocalized electrons'

The diagram above represents the arrangement of atoms in

When combined, the TWO elements that form an ionic compound are

Which of the elements form a chloride that is ionic in nature?

Melting Point: $973$ K, Boiling Point: $1693$ K

Melting Point: $463$ K, Boiling Point: $453$ K

Melting Point: $248$ K, Boiling Point: $348$ K

Melting Point: $193$ K, Boiling Point: $333$ K

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

$\text{H}_2\text{O}_2$

During the electrolysis of aqueous copper(II) sulfate solution in which inert electrodes are used, the ions migrating to the cathode are

$\text{Cu}^{2+}(\text{aq})$ and $\text{H}^+(\text{aq})$

$\text{H}^+(\text{aq})$ and $\text{OH}^-(\text{aq})$

$\text{SO}_4^{2-}(\text{aq})$ and $\text{OH}^-(\text{aq})$

$\text{Cu}^{2+}(\text{aq})$ and $\text{SO}_4^{2-}(\text{aq})$

Three grams of sodium hydrogen carbonate are added to $100\text{ cm}^3$ of $0.2\text{ mol dm}^{-3}$ hydrochloric acid in order to prepare a sample of sodium chloride. The number of moles of hydrochloric acid used in this reaction is

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

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

A solution was formed by mixing $25.0\text{ g}$ of aluminium sulfate with $100\text{ mL}$ of distilled water. The temperature change was $4\text{ }^\circ\text{C}$ . What is the heat given off in forming the solution? (Note: $Q = mc\Delta T$ ; $c = 4.18\text{ J/g}^\circ\text{C}$ ; density of water = $1\text{ g/mL}$ .)

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

Which of the following graphs shows the effect of concentration on the rate of reaction?

Graph showing a linear increase of $1/t$ with concentration.

Graph showing a linear decrease of $1/t$ with concentration.

Graph showing an exponential increase of $1/t$ with concentration.

Graph showing a curve leveling off of $1/t$ with concentration.

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

The equation (where $I$ = current, $t$ = time) used to calculate the quantity of electricity generated during electrolysis is given by

The experiment above shows that magnesium oxide is

A standard solution can be defined as a solution of

I. a fixed volume II. known mass concentration III. unknown molar concentration

Which of the following halogens is a liquid at room temperature?

Which of the following metals reacts readily with water to produce a strongly alkaline solution?

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

When copper(II) carbonate is heated alone in a dry test tube, a gas is evolved and a black residue is formed. This gas is expected to

turn red litmus blue

relight a glowing splint

decolourize acidified aqueous potassium manganate(VII)

form a white precipitate with aqueous calcium hydroxide

What type of reaction occurs when zinc metal is added to copper sulfate solution?

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

$\text{H}_2\text{S}$

Which of the following is/are produced when carbon monoxide reacts with iron(III) oxide?

$\text{CO}_2$ and $\text{CO}$ only

$\text{CO}_2$ and $\text{Fe}$ only

Which of the following pairs of reagents would result in the formation of a yellow precipitate?

$\text{Fe}_2(\text{SO}_4)_3(\text{aq})/\text{NH}_3(\text{aq})$

$\text{CuSO}_4(\text{aq})/\text{NH}_3(\text{aq})$

$\text{Pb}(\text{NO}_3)_2(\text{aq})/\text{KI}(\text{aq})$

$\text{FeSO}_4(\text{aq})/\text{NaOH}(\text{aq})$

Which of the following gases forms white fumes when it reacts with a glass rod that was dipped in aqueous ammonia?

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

Which of the following aqueous solutions will produce a blue precipitate with aqueous sodium hydroxide?

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.

How many covalent bonds are there in a nitrogen molecule?

the same as aluminium

a compound of metals

Which of the following statements are true of alkanes and alkenes?

I. Both alkanes and alkenes burn in air to give carbon dioxide and water. II. Alkanes undergo substitution reactions while alkenes undergo addition reactions. III. Alkanes are saturated hydrocarbons whilst alkenes are unsaturated hydrocarbons.

Ethene is described as being unsaturated. This means that the

molecule has insufficient hydrogen atoms

molecule contains at least one double bond

carbon atoms in the molecule are very reactive

carbon atoms in ethene are linked by single bonds

To which homologous series does the structure belong?

Which of the following molecules could be obtained by cracking the alkane $C_{16}H_{34}$ ? I. $C_{2}H_{4}$ II. $C_{6}H_{14}$ III. $C_{10}H_{20}$

What is the name of the catalysed reaction which uses an alcohol and an organic acid?

Which of the following formulae represents pentane?

Which of the following types of reactions occurs between pentane and bromine?

Which of the following is the residue which is found in the fractional distillation of petroleum?

Which of the following options correctly defines the term 'structural isomerism'?

Organic compounds with a different molecular formula but the same structural formula

Organic compounds with the same molecular formula and the same structural formula

Organic compounds with the same molecular formula but a different structural formula

Organic compounds whose molecular formula and structural formula are different

Which of the following is a natural source of hydrocarbons?

For Conversion II, ethyl ethanoate is heated under reflux with a reagent and ethanol is produced. The name of the reagent is

The reaction can be classified as

addition polymerization

condensation polymerization

It is better to use soapless detergents for washing in hard water than it is to use soap because soapless detergents

are cheaper than soaps

are more biodegradable than soaps in hard water

form an insoluble scum in hard water

are more soluble in hard water than soaps

CSEC Chemistry Paper 1 January 2025 - Free CXC Past Paper with Answers

CSEC Chemistry Paper 1 January 2025 Questions