June 22 JAMB CHEMISTRY QUESTIONS AND ANSWERS 2021

Here is a list of possible questions for june 23, good luck. This is not the actual questions but can come out based on our analysis
1. An element X has two isotopes
20
10X and
22
10X present in the ratio
1:3. The relative atomic mass of x
would be
A. 20.5
B. 21.0
C. 21.5
D. 22.0
2. 200cm3 of oxygen diffuse
through a porous plug in 50
seconds. How long, will 80cm3 of
methane (CH4) take to diffuse
through the same porous plug
under the same conditions?
A. 40sec
B. 20sec
C. 14sec
D. 7sec
3. Which of the following terms
indicates the number of bonds
that can be formed by an atom?
A. oxidation number
B. Valence
C. Atomic number
D. Electronegativity
4.
The diagram above represents an
atom of
A. magnesium
B. helium
C. chlorine
D. neon
5. Which of the following gases is
the most dangerous pollutant?
A. Hydrogen sulphide.
B. Carbon Monoxide
C. Sulphur(iv)oxide
D. Carbon Dioxide
6. A Side effect or Soft water is
that.

A. It gives offensive taste
B. excess calcium is precipitated
C. it attacks lead contained in
pipes
D. it encourages the growth of
bacteria.
7. Farmlands affected by crude oil
spillage can be decontaminated
by
A. adding acidic solutions
B. using aerobic bacteria
C. pouring water on the affected
area
D. burning off the oil from the
area
8. Which of the following
functional groups will give gas
bubbles when treated with a
saturated solution of sodium
hydrogen trioxocarbonate(iv)?
A. —NH3
C. —OH
D. >C = 0
9. The oxidation state of Cr in
K2Cr2O7 is
A. +7
B. +6
C. +5
D. 4
10. 2Na2O2(s) + 2H2O(l) → 4Na0H(s)
+ O2
The substance that is oxidized in
the reaction above is
A. 2Na2O2(s)
B. NaOH(aq)
C. H2O(l)
D. O2(g)
11.
Z in diagram above represents
A. heat of reaction

16. The iron (iii) oxide impurity in
bauxite can be removed by
A. fractional crystallization in acid
solution
B. dissolution in sodium hydroxide
and filtration
C. extraction with concentrated
ammonia and reprecipitation
D. electrolysis of molten mixture
17. Aluminium is extracted
commercially from its ore by
A. heating aluminium oxide with
coke in a furnace
B. the electrolysis of fused
aluminium oxide in cryolite
C. treating cryolite with sodium
hydroxide solution under pressure
D. heating sodium aluminium
silicate to a high temperature.
18. Which of the following
compounds gives a yellow residue
when heated and also reacts with
aqueous sodium hydroxide to give
a white gelatinous precipitate
soluble in excess sodium
hydroxide solution?
A. (NH4)2CO3
B. ZnCO3
C. Al2(SO4)3
D. PbCO3
19. The least easily oxidized of
the metals below is
A. Cu
B. Na
C. Zn
D. Al
20. Which of the following
chlorides would exhibit the least
ionic character?
A. MgCl2
B. CaCl2
C. LiCl
D. AlCl3
21. Which of the following
CANNOT be obtained by fractional
distillation of petroleum?

B. activation energy
C. free energy
D. entropy of reaction
12. The nucleus of an atom
contains
A. protons only
B. neutrons only
C. protons and electrons
D. protons and neutrons
13. Which of the following does
NOT happen when a Zinc rod is
introduced into a solution of
Copper (II) sulphate?
A. Electrons flow towards the zinc
rod
B. The Zinc rod dissolves
C. The temperature of the soil
chances
D. The blue colour of the solution
gradually disappears.
14. Which of the following
statements is correct during the
electrolysis of a caustic soda
solution using platinum
electrodes?
A. Oxygen gas is given off at the
cathode
B. Hydrogen gas is given off at
the anode
C. Sodium metal is deposited at
the cathode
D. Alkalinity at the cathode
increases.
15. Which of the following
statements is INCORRECT?
A. Fractional distillation of crude
petroleum will give the following
hydrocarbon fuels in order of
increasing boiling point. Butane <
Petrol < Kerosene
B. H2C = CH2 will serve as a
monomer in the preparation of
polythene
C. both but-i-ene and but-i-yne
will decolourize bromine readily
D. Calcium carbide will react with
water to form any alkyne

B. p-orbitals
C. d-orbitals
D. f-orbitals
28. A particle that contains 11
protons, 12 neutrons and 10
electrons is probably a
A. Neutral non-metal
B. metallic ion
C. non-metallic ion
D. neutral metal.
29. A catalyst increases the rate
of a chemical reaction by
providing a path that
A. raises the activation energy
B. increases the temperature
C. lowers the activation energy
D. increases the concentration
30. A metal M displaces Zinc from
ZnCl2 solution. This shows that
A. electrons flow from Zinc to M
B. M is more electropositive than
Zinc
C. M is more electronegative than
Zinc
D. Zinc is more electropositive
than M.
31. Calculate the quantity of
electricity in coulombs required to
liberate 10g of copper from a
copper compound.
A. 32395.5
B. 30156.3
C. 60784.5
D. 15196.6
[Cu 64 F = 96500c]
32. The IUPAC names for the
compounds CH3COOH and
CH2=CH2 are respectively
A. acetic acid and ethane
B. ethanoic- acid and ethene
C. methanoic acid and ethylene
D. ethanol and ethene.
33. The boiling point of water is
higher than that of methanol
because

A. water is an oxide while
methanol is an alcohol
B. inter-molecular forces in water
are stronger than those in
methanol
C. Water is an inorganic
compound while methanol is
organic
D. Water is a compound while
methanol is a covalent compound
34. If an element x of atomic
number Z and mass number y is
irradiated by an intense
concentration of neutrons, the
relevant nuclear equation is
A. ZYx + 10n → y-1z+1x
B. YZx + 10n → y+1zx
C. YZx + 10n → yz+1x
D. YZx + 10n → y+1z-1x
35. Which combination of the
following statements is correct?
1. Lowering the activation energy
2. conducting the reaction in a
gaseous state.
3. Increasing the temperature.
4. removing the products as soon
as they are formed.
5. Powdering the reactant if solid
A. 1, 2 and 3
B. 1, 3 and 5
C. 2, 3 and 5
D. 3 and 4
36. An element with atomic
number twelve is likely to be
A. electrovalent with a valency of
1
B. electrovalent with a valency of
2
C. covalent with a valency of 2.
D. covalent with valency of 4.
37. Which of the following
physical properties decreases
across the periodic Table?
A. ionization potential
B. Electron affinity
C. Electronegativity
D. Atomic radius.

38. If a gas occupies a container
of volume 146cm3 at 18⁰c and
0.971 atm, its volume in cm3 at
s.t.p is
A. 133
B. 146
C. 266
D. 292
39. 50cm3 of carbon (ii) oxide
was exploded with 150cm3 of air
containing 20% oxygen by
volume, which of the reactants
was in excess?
A. Carbon (ii) oxide
B. Carbon (iv) oxide
C. Oxygen
D. Nitrogen
40. The formula CH2O for ethanoic
acid is regarded as its
A. molecular formula
B. general formula
C. empirical formula
D. Structural

1. C 2. C 3. B 4. A 5. D 6. C 7. A
8. B 9. B 10. A 11. A 12. D 13. A
14. D 15. D 16. B 17. B 18. B
19. C 20. D
21. D 22. B 23. C 24. D 25. D
26. C 27. C 28. B 29. C 30. B
31. D 32. B 33. B 34. B 35. B
36. B 37. D 38. A 39. C 40. C