4.
What is the atomic number of the element represented by the following diagram?
- (A)
7
- (B)
9
- (C)
10
- (D)
19
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CSEC Chemistry Paper 1 January 2021 - Free CXC Past Paper with Answers
Free CXC Chemistry Paper 1 January 2021 past paper from 2021. Includes a worked answer key. Open the PDF, take a timed test, and study with AI on Caribbean AI.
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Which of the following processes demonstrates that matter is made up of minute particles?
Diffusion
Capillarity
Distillation
Evaporation
In which of the following situations is Brownian motion demonstrated?
The scent of perfume moving from one part of a room to another
The swelling of red beans when soaked in water
Loss of heat from a hot body to a cold body
Pollen grains moving at random in water
Particles of a solid cannot move about freely because the
particles cannot be easily compressed
forces of attraction are very strong
forces of attraction are very weak
particles have a high density
What is the atomic number of the element represented by the following diagram?
7
9
10
19
Which of the following substances supplies protons as the only positive ions in aqueous solutions?
Salt
Base
Acid
Alkali
In the notation Cl the number 17 represents the
charge
mass number
oxidation state
atomic number
The following table shows the melting and boiling points of the chlorides of four elements represented by the options A, B, C and D.
Which of these elements form a chloride that is ionic in nature?
973 / 1693
463 / 453
248 / 348
193 / 333
When 100 cm³ of 2 mol dm⁻³ hydrochloric acid (in excess) are added to 5.0g of granulated zinc, hydrogen gas is evolved at a certain rate. If 5.0 g of powdered zinc were used instead, the rate of production of hydrogen gas would
increase because of the greater concentration of powdered zinc
increase because of the increased surface area of powdered zinc
decrease because of the decreased surface area of powdered zinc
decrease because of the lower solubility of powdered zinc
Which of the following processes may be used to separate a mixture of plant pigments?
Centrifugation
Solvent extraction
Fractional distillation
Paper chromatography
Which of the following properties are true of covalent compounds? I. Mainly solids II. Usually insoluble in water III. Usually have low melting and boiling points
I and II only
I and III only
II and III only
I, II and III
What is the volume, in dm³, of gaseous product collected at RTP when 0.2 mol of CH₄ burns in excess oxygen according to the following equation? CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) 1 mol of gas at RTP occupies 24 dm³
4.8
9.6
14.4
24.0
Which of the following substances do NOT produce water when reacted with acid?
Carbonates
Metal oxides
Active metals
Metal hydroxides
The ions of alkaline earth metals always have a charge that is
neutral
variable
+1
+2
Which of the following lists of mixtures is arranged in order of INCREASING particle size?
Solutions, colloids, suspensions
Solutions, suspensions, colloids
Colloids, solutions, suspensions
Suspensions, colloids, solutions
Which of the following compounds is covalent?
Potassium chloride
Calcium chloride
Hydrogen chloride
Magnesium chloride
Item 16 refers to the following energy profile diagram.
From the energy profile diagram above, it can be said that the reactants
cannot be converted into products
absorb energy to form products
give out heat when they react
give energy to products
Which of the following statements concerning Group VII elements is NOT correct?
They form negative ions by losing one electron.
They form negative ions by gaining one electron.
They have one electron less than a stable electronic configuration.
They exist as diatomic molecules.
Which of the following reactants was used in liberating a gas that turns moist red litmus paper blue?
Methyl orange
Barium chloride
Calcium carbonate
Magnesium metal
A salt was heated with a certain acid. A gas evolved and turned moist red litmus paper blue. Which of the following does the salt contain?
Nitrate(V)
Ammonium
Sulfate(VI)
Carbonate
Which of the following electronic configurations represents an atom which will MOST readily form a positive ion?
2, 7
2, 8, 2
2, 8, 7
2, 8, 8, 2
The diagram above represents the arrangement of atoms in
sulfur
benzene
graphite
diamond
Which of the following mass of oxygen atoms contains the same number of moles as 112 g of sulfur atoms? [RAM: O = 16; S = 32]
0.56 g
5.60 g
56.00 g
560.00 g
The bond between the two carbon atoms is
triple
single
dative
double
Which of the following compounds is soluble in cold water?
Lead sulfate
Lead nitrate
Lead chloride
Lead carbonate
anode is 0.005 g
anode is 0.005 g
anode is 0.325 g
cathode is 0.005 g
cathode is 0.325 g
Three grams of sodium hydrogen carbonate are added to 100 cm³ of 0.2 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
Which of the following compounds is NOT a normal salt?
Potassium nitrate
Sodium carbonate
Potassium carbonate
Sodium hydrogen carbonate
When a concentrated solution of sodium chloride is electrolysed using carbon electrodes,
chlorine is liberated at the anode
sodium is liberated at the cathode
the solution at the anode is acidic
the solution at the cathode is acidic
Which of the following compounds is oxidized?
Which of the points on the graph above represents the neutralization point of the reaction?
P
Q
R
S
If substances containing one mole of solute per dm³ are investigated, which substance should cause the bulb to glow BRIGHTEST?
Water
Ammonia
Sulfuric acid
Ethanoic acid
Which of the following substances, when added to pure water, significantly increases the water's conductivity?
Graphite
Sodium chloride
Iron(II) hydroxide
Copper(II) hydroxide
Which of the following ions requires the LARGEST number of moles of electrons to liberate one mole of it?
Al³⁺
Cl⁻
Cu²⁺
O²⁻
Which of the following processes correctly describes the reaction above?
Decomposition
Neutralization
Precipitation
Reduction
An ion with a single negative charge may be converted into a neutral atom of the same element by
losing a neutron
gaining a proton
losing an electron
gaining an electron
Which of the following halogens is a liquid at room temperature?
Iodine
Fluorine
Chlorine
Bromine
Which of the following properties is common to both copper and calcium?
Reacting with dilute hydrochloric acid
Forming of coloured aqueous solutions
Having variable oxidation states
Forming of ions with a charge of +2
What type of reaction occurs when zinc metal is added to copper sulfate solution?
Combustion
Neutralization
Displacement
Decomposition
It was found that magnesium metal displaces zinc ions in zinc sulfate, while zinc metal displaces lead ions in lead sulfate.
What is the order of reactivity of the metals, from most reactive to least reactive?
Zn, Mg, Pb
Zn, Pb, Mg
Pb, Zn, Mg
Mg, Zn, Pb
Which of the following methods is used for the extraction of aluminium?
Electrolysis of its molten oxide
Reduction of its oxide using coke
Electrolysis of its aqueous chlo- ride
Reduction of its oxide using carbon monoxide
Which of the following is/are true of metals? I. They are reducing agents. II. They are capable of replacing hydrogen in acids to form salts. III. They are generally poor conductors of electricity.
I only
II only
I and II only
I and III only
Which of the following outcomes is observed when EXCESS aqueous ammonia is added to a solution of copper(II) sulfate?
Green solution
Green precipitate
Deep blue solution
Light blue precipitate
Which of the following compounds may be used to counteract the effects of acid rain on the soil?
CO
SO,
H₂S
CaO
A solution has a pH of 1. This solution would be expected to react with
zinc metal to produce hydrogen
hydrochloric acid to produce chlorine
zinc metal to produce a solution of pH 10
hydrochloric acid to produce a salt and water
Item 45 refers to the following information. A compound when treated with concentrated hydrochloric acid gives off a greenish- yellow gas which bleaches moist red litmus paper.
The gas given off is
chlorine
sulfur dioxide
hydrogen sulfide
nitrogen dioxide
Copper and aluminium are both good conductors of electricity, but aluminium is preferred to copper for overhead electrical cables because
aluminium is obtained in a very high degree of purity
aluminium is lighter and resistant to corrosion
copper, a transition metal, forms a coloured coating
copper rapidly reacts with the grease present in air
An alloy is
the same as aluminium
a compound of metals
a mixture of metals
a type of element
Item 48 refers to the following equation. H H H H H-C-C=C-C-H + Br₂ → X H H
What is the structural formula for X?
The existence of millions of organic compounds is due primarily to the ability of carbon to form I. multiple bonds II. ring structures III. branched chains
I and II only
I and III only
II and III only
I, II and III
Compounds I and II are known as the
isomers of C,H,O
isotopes of C,H,O
condensed formulae of C₂H₂O
molecular formulae of C,H,O
Items 51-52 refer to the following options. (A) Addition (B) Isomerism (C) Esterification (D) Polymerization In answering Items 51-52, each option may be used once, more than once or not at all.
What is the name of the process in which proteins are formed from amino acids?
Addition
Isomerism
Esterification
Polymerization
What is the name of the catalysed reaction which uses an alcohol and an organic acid?
Addition
Isomerism
Esterification
Polymerization
Which of the following tests can be used to distinguish between an alkane and an alkene? I. Adding bromine solution II. Burning III. Conductivity
I only
II only
III only
I and III only
In which of the following reactions is ethene produced from ethanol?
Hydrolysis
Dehydration
Esterification
Saponification
Which of the following organic compounds has a pH less than 7?
Natural gas
Propene
Ethanol
Vinegar
The compound 2-bromobutane has a structural formula of
ALL members of a homologous series have similar
densities
boiling points
chemical properties
physical properties
Which of the following is NOT formed from condensation polymerization?
Polysaccharides
Polyalkenes
Polyamides
Polyesters
Which of the following substances is a product of a halogenation reaction with methane?
Nitrogen(IV) oxide
Hydrogen chloride
Ammonia
Water
Which of the following structures represents a compound that can react with an alcohol to produce a sweet smelling liquid?
