CSEC Chemistry Paper 1 May/June 2003 - Free CXC Past Paper with Answers

Which of the following apparatus/instruments is most suitable for obtaining both cooking oil and water from a mixture of the two?

Fractionating column

Which TWO of the following statements are true about the arrangement of electrons, protons and neutrons in an atom? I. Protons and neutrons are found in the nucleus. II. Electrons can be found anywhere outside the nucleus. III. The number of protons always equals the number of neutrons. IV. The number of protons always equals the number of electrons.

Which of the following compounds may be conveniently prepared by precipitation?

Copper (II) sulphate

Which of the atoms represented below by their electronic configuration will most readily form a positive ion?

In descending Group VII of the periodic table, which TWO of the following trends occur? I. The density of the elements increases II. The relative atomic mass of the elements decreases III. The melting point of the elements increases IV. The reactivity of the elements increases

Dilute sulphuric acid is classified as a strong acid because it

produces 2 moles of hydrogen ions per mole of acid

requires 2 moles of sodium hydroxide for neutralisation

is almost completely ionised and is a good conductor of electricity

ionises to give both hydrogen ions and sulphate ions

When a saturated solution of copper (II) sulphate is cooled, crystals of copper (II) sulphate-5-water begin to form because solubility of copper (II) sulphate-5-water

increases with decreasing temperature

decreases with increasing temperature

decreases with decreasing temperature

increases with increasing temperature

The arrangement of elements in the periodic table is based on

relative atomic mass

relative molecular mass

When iron (III) sulphate reacts with aqueous potassium iodide, a brown colouration of iodine is produced. Which of the following deductions is correct?

Iron (III) sulphate is a reducing agent.

The iodide ion, I⁻, has been oxidised to iodine.

The iron (III) sulphate has lost electrons.

The iodide ion, I⁻, has gained electrons.

Which of the following statements about sodium metal are CORRECT? I. It contains Na⁺ ions and mobile electrons. II. It contains Na⁺ ions and mobile electrons. III. It contains cations which repel each other. IV. It contains anions which repel each other.

When aqueous silver nitrate is added to an aqueous solution of magnesium chloride, a white precipitate forms. The ionic equation for the formation of this precipitate is

Mg²⁺(aq) + NO₃⁻(aq) = MgNO₃(s)

Ag⁺(aq) + 2Cl⁻(aq) = AgCl₂(s)

Mg²⁺(aq) + 2NO₃⁻(aq) = Mg(NO₃)₂(s)

Ag⁺(aq) + Cl⁻(aq) = AgCl(s)

In which TWO of the following equations are the UNDERLINED reagents acting as oxidising agents?

When crystals of potassium nitrate are dissolved in water, the temperature of the solution decreases because

little energy is required to break down the crystal structure of the potassium nitrate

heat is always absorbed when a substance dissolves

the energy content of dissolved potassium nitrate is higher than that of solid potassium nitrate

potassium nitrate is colder than water

The high melting point of ionic compounds may be due to the

large numbers of ions

attraction among ions

Which of the following statements about chemical reactions is NOT correct?

Energy is given out when bonds break and taken in when bonds form.

Chemical reactions involve the making and breaking of bonds.

Endothermic reactions take energy from the surroundings.

Exothermic reactions give energy to the surroundings.

A substance that conducts an electric current but remains chemically unchanged is

aqueous copper (II) sulphate

solid sodium chloride

Which of the following can exactly neutralise 20 cm³ of 2.0 mol dm⁻³ sodium hydroxide?

I. 10 cm³ of 4.0 mol dm⁻³ hydrochloric acid

II. 10 cm³ of 2.0 mol dm⁻³ sulphuric acid

III. 20 cm³ of 4.0 mol dm⁻³ nitric acid

Some calcium carbonate was reacted with excess dilute hydrochloric acid. The volume of carbon dioxide evolved was recorded and plotted against time. Which of the following graphs represents this reaction?

In which of the following processes is fractional distillation NOT used?

Refining of crude petroleum

Separation of methanol from a methanol-water mixture

Separation of chlorophyll in a leaf extract

Separation of liquid air into nitrogen and oxygen

Graphite can be used as a lubricant because of

strong attraction between the hexagonal layers of carbon atoms

weak attraction between the hexagonal layers of carbon atoms

the loose electrons which can move throughout the lattice

strong attraction within the hexagonal layers of carbon atoms

Which of the following sulphates are insoluble? I. Barium sulphate II. Magnesium sulphate III. Lead sulphate IV. Aluminium sulphate

The mass of an element produced in electrolysis is proportional to the I. quantity of electricity which has been passed II. volume of the electrolyte III. mass of the electrolyte IV. mass of the electrode

Which of the following statements BEST characterises a catalyst?

It increases the activation energy of the reaction.

It alters the quantity of the products formed.

It is always unchanged physically at the end of a reaction.

It is always unchanged chemically at the end of a reaction.

Which of the following operations results in sublimation?

Heating of solid sodium chloride

Cooling of oxygen gas

Heating of iodine crystals

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

Which of the following sources of energy is the MOST commonly used in the world today?

Which of the following methods can be used to compute the value of -B kJ? I. Energy of Z minus the energy of X and Y II. Energy of X and Y minus the energy of Z III. The sum of the energies of X, Y and Z

Which of the following processes provides evidence in support of the particulate nature of matter?

Sulphuric acid forms the sodium salts NaHSO₄ and Na₂SO₄. Its basicity is therefore

A sample of substance N was placed in solution M. Which of the following diagrams represents pairs of experiments that would be most suitable to determine how the concentration of M affects the rate of the reaction?

Atoms of isotopes, X and Y, have I. the same number of electrons. II. the same number of protons. III. different numbers of neutrons.

Which of the following could produce carbon dioxide and carbon monoxide as pollutants? I. Geothermal energy II. Solar energy III. Fossil fuels IV. Biogas

At 1 atmospheric pressure, the particles move fastest in a

Which of the following pairs of acids is monobasic?

HNO₃ and H₂SO₄

CH₃CO₂H and HO₂CCO₂H

All of the following gases are colourless EXCEPT

Which of the following elements reacts most vigorously with H⁺(aq) ions to give hydrogen gas?

Which of the following is a weak electrolyte?

Aqueous ethanoic acid

Dilute hydrochloric acid

Item 38 refers to the following diagrams.

In which of the experiments would the amount of carbon dioxide collected be GREATEST?

Which of the following gives an alkaline reaction with moist litmus paper?

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

Which of the following statements is true?

Ammonia is an acidic gas.

Ammonia is soluble in water and functions as a base.

Nitric acid is used as a fertilizer and a reducing agent.

Nitric acid contains two replaceable hydrogen atoms.

Aluminium is more reactive than iron yet, after a while, a piece of aluminium left exposed to the atmosphere becomes corrosion resistant whilst a similar piece of iron continues to corrode. This is because the

aluminium has reacted completely

iron oxide formed is more reactive than the aluminium oxide formed

oxide film on aluminium protects the metal from further corrosion but the oxide film on iron does not

iron oxide reacts with the iron below but aluminium oxide does not react with the aluminium below

Which of the following methods is used for the extraction of metals at the top of the electrochemical series?

Electrolysis of molten chloride

Electrolysis of aqueous chloride

Electrolysis of molten oxide

Reduction of oxide with carbon

Which of the following metals will NOT react with water under any conditions?

Which of the following observations would you expect to make when excess sodium hydroxide solution is added to a solution containing zinc ions?

An alkaline gas produced

White precipitate soluble in excess

White precipitate insoluble in excess

A green precipitate insoluble in excess

Items 46-47 refer to the following organic compounds. (A) Ethanol (B) Ethene (C) Ethanoic acid (D) Ethyl ethanoate

In answering items 46-47 a particular choice from the above may be made more than once, once, or not at all.

Which of the organic compounds

undergoes addition reactions?

is immiscible with water and is sweet-smelling?

A compound has the following structural formula.

Which TWO of the following statements are correct? The compound I. is an alcohol. II. is a branched alkane. III. can react with sodium. IV. is an unreactive substance.