JAMB Chemistry Previous Year Questions: 2022 | Chemistry for JAMB PDF Download

Q1: The sub-atomic particles located in the nucleus of an atom are?
(a) neutron and proton
(b) proton and electron
(c) proton and ions
(d) neutron and electron
Ans: (a)
Nucleons have protons and neutrons. The protons contain the positive charge of an atom and the neutrons are neutrally charged. Electrons, which are negatively charged, are located outside of the nucleus.

Q2: The IUPAC nomenclature of the structure shown is?
(a) 3-chloro-3-methylbutane
(b) 2,2,-dichloro-3-methylbutane
(c) 3-methylchlorobutane
(d) 2-chloro-2-methylbutane
Ans: (d)
Alkanes consist of single-bonded carbon and hydrogen atoms and lack any other functional groups. 

Q3: SO₂ +  O₂  ? 2SO₃
the reaction above, the most suitable catalyst is?
(a) chromium(vi)oxide
(b) iron(iii)oxide
(c) copper(i)oxide
(d) vanadium(v)oxide
Ans: (d)
The contact Process is an industrial method of producing sulfuric acid during which sulfur dioxide is converted into sulfur trioxide, by passing sulfur dioxide and oxygen over a solid vanadium(V) oxide catalyst.

Q4: In the preparation of salts, the method employed will depend on the?
(a) composition
(b) dissociating ability
(c) stability to heat
(d) precipitating ability
Ans: (c)

• solubility of the salt in water
• heat stability of the salt

Q5: The following non-metal form acidic oxides with oxygen except?
(a) phosphorus
(b) sulphur
(c) carbon
(d) chlorine
Ans: (c)

Carbon monoxide is a neutral oxide as it neither reacts with acids nor reacts with bases.
Carbon monoxide is produced when combustion reactions are not fully completed, either through lack of oxygen or due to low mixing.

Q6: How many neutrons are present in an atom with the mass number and atomic number 37 and 17 respectively?
(a) 18
(b) 20
(c) 37
(d) 17
Ans: (b)
mass number = number of neutrons + atomic number
number of neutrons = mass number - atomic number
⇒ 37 - 17 = 20

Q7: The sulphide that is commonly used in coating electric fluorescent tubes is?
(a) iron(ii)Sulphide
(b) tin(ii)sulphide
(c) Zinc Sulphide
(d) lead(iv) Sulphide
Ans: (c)
ZnS (Zinc Sulfide) as it emits a flash of light when struck by an alpha particle by a phenomenon known as Radio luminescence in which a flash of light is observed on the screen when acted upon by a radioactive substance.

Q8: An organic compound which liberates carbon(iv)oxide from trioxocarbonate(iv) solution is likely to be?
(a) C₂H₅OH
(b) C₂H₄
(c) C₆H₆
(d) CH₃COOH
Ans: (d)

• Carboxylic acid is an organic compound containing a carboxyl functional group.
• Carboxylic acids and Enols react with sodium bicarbonate to liberate carbon dioxide.

Q9: The addition of sodium chloride to water to form a solution would lead to?
(a) increase in freezing point and increase the boiling point
(b) increase in freezing point and decrease the boiling point
(c) decrease in freezing point and decrease the boiling point
(d) decrease in freezing point and increase the boiling point
Ans: (d)
Adding salt to water lowers its freezing point and raises its boiling point.

Q10: A chemical widely used as a fertilizer is?
(a) galena
(b) bauxite
(c) emerald
(d) nitrochalk
Ans: (d)
Calcium Ammonium Nitrate or CAN (nitro-limestone or nitrochalk), is a widely used inorganic fertilizer.

Q11: On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell
(a) cu²⁺
(b) sn²⁺
(c) fe²⁺
(d) zn²⁺
(a)
Electrochemical series (also known as activity series of elements) is a series in which elements are arranged in an increasing or decreasing order of their standard electrode potential.
K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Ag > Au.

Q12: The addition of charcoal to the filter bed of sand during water treatment for city supply is to?
(a) prevent goiter
(b) prevent tooth decay
(c) remove odour
(d) kill germs
Ans: (c)
The addition of charcoal is to adsorb the radioactive gases within the air vacuumed from a nuclear boiling water reactor turbine condenser and retain them while they rapidly decay to non-radioactive solid species.

Q13: Using the metal activity series, the metal that can liberate hydrogen gas from steam is?
(a) iron
(b) copper
(c) tin
(d) lead
Ans: (a)
The reaction of Iron with steam forms iron oxide and hydrogen gas

Q14: An organic compound with a fishy smell is likely to have a general formula ___
(a) RCONHR¹
(b) RCONH₂
(c) RNH₂
(d) RCOR¹
Ans: (c)
Amines derive from ammonia (NH₃) in which one or more hydrogen atoms are replaced by an alkyl or aryl group.

Q15: N₂O₄ ? 2NO₂        (? = -ve)
From the reaction above, which of these conditions would produce the highest equilibrium yield for N₂O₄?
(a) Low temperature and high pressure
(b) Low temperature and low pressure
(c) high temperature and low pressure
(d) high temperature and high pressure
Ans: (a)

Low temperature and high pressure favour the highest yield for N₂O₄

Q16: Zn + 2HCL ? ZnCl₂ + H₂
What happens to zinc in the above reaction?
(a) oxidized
(b) a reactant
(c) reduced
(d) a metal
(a)
Zinc will be oxidized because it is a reducing agent where as HCl is an oxidizing agent.

Q17: An organic functional group which would likely decolourize ammoniacal silver nitrate is?
(a) alkene
(b) alkane
(c) alkyne
(d) alkanol
Ans: (c)
Terminal alkynes react with Tollens reagent (ammoniacal silver nitrate solution) to form silver alkynides as a white precipitate, whereas internal alkynes do not react with Tollens reagent.

Q18:  coloured gas that is known to be poisonous and can readily damage the mucous lining of the lungs is?
(a) hydrogen sulphide
(b) carbon(ii)oxide
(c) chlorine
(d) sulphur(iv)oxide
Ans: (c)
Much exposure to chlorine gas can cause coughing, eye and nose irritation, lacrimation, and a burning sensation in the chest. This can degenerate to airway constriction, noncardiogenic pulmonary edema, hemoptysis, and bronchopneumonia

Q19: In order to electroplate spoon with silver, the arrangement of the electrolytic cell is?
(a) the anode is a silver rod and the cathode is the spoon
(b) the anode is the spoon and the cathode is a silver rod
(c) the electrolyte is silver trioxonitrate(v)( solution and the cathode is a silver rod.
(d) the electrolyte is silver trioxonitrate(v) solution and the anode is the spoon
Ans: (a)
The steel spoon to be coated with silver is the cathode of the electrolytic cell. The anode of the electrolytic cell is made of silver metal and the electrolyte used for electroplating silver on a spoon must contain silver ions (Ag + ), for example, silver nitrate (AgNO₃) or silver cyanide (AgCN) dissolved in water.

Q20: An organic compound which decolorizes bromine water is likely to be?
(a) C₃H₈
(b) C₂H₆
(c) C₄H₁₀
(d) C₂H₄
Ans: (a)
Mixing an alkene with bromine water (or bubbling a gaseous alkene through bromine water) results in a colourless solution.

Q21: Crude petroleum is converted to useful products by the process of?
(a) fractional crystallization
(b) fractional distillation
(c) filtration
(d) chromatography
Ans: (b)
Fractional distillation is a process used in crude oil refineries to separate (as well as join or split) the various lengths of hydrocarbon chains to create different petroleum products from the different distillates. More.

Q22: An organic compound contains 69% carbon, 15.3% hydrogen and 30.7% oxygen. Calculate the the empirical formula [C=12, H = 1, O = 16]
(a) C₄H₁₂O
(b) C₃H₉O
(c) C₄H₉O
(d) C₃H₈O
Ans: (d)

Q23: 2H₂ + O₂ ? 2H₂O
From the equation above, calculate the volume of unreacted oxygen gas if a mixture of 50cm³  of hydrogen and 75cm³  of oxygen is involved
(a) 85cm
(b) 50cm
(c)125cm
(d) 55cm
Ans: (b)
From the given equation, 2 mol H₂ reacted with 1 mol of O₂
50cm³  hydrogen reacted with 25cm³  oxygen
remainder oxygen = supplied amount - reacted amount
⇒ 75cm³ - 25cm³
= 50cm³

Q24: In which of the following will hydrogen form an ionic compound?
(a) HCL
(b) NaH
(c) NH₃
(d) CH₄
Ans: (b)
NaH ionic hydride which is also known as saline (salt-like) hydride, composed of Na+ and H⁺ ions

Q25: If the volume of a given mass of a gas at 0ºc is 29.5cm³ . What will be the volume of the gas at 15ºc, given that the pressure remains constant?
(a) 31.6
(b) 62.2
(c) 32.7
(d) 31.1
Ans: (d)
Charles' law states that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature if the pressure remains constant.
Given that:
V₁ = 29.5cm³
V₂ = ?
T₁ = 0ºc or 273k
T₂ = 15ºc or 288k

V₂ = 31.1cm³

Q26: The reactions below represent neutralization reactions, in which of them is the value of ?H highest?
(a) CH₃CH₂COOH + KOH ? CH₃CH₂COOK + H₂O
(b) NH₄OH + HCL ? NH₄ + H₂O
(c) NaOH + HCL ? NaCL + H₂O
(d) CH₃COOH + NaOH + CH₃COONa + H₂O
Ans: (c)
Enthalpy changes of neutralization are always negative - heat is released from the reaction of an acid and an alkali.
Such enthalpy changes are smaller in magnitude compared to that between the reaction of strong acids and strong bases.

Q27: The pollutant that is usually present in a city which generates its electricity from coal?
(a) fog
(b) carbon(ii)oxide
(c) smog
(d) sulphur(iv)oxide
Ans: (d)
Sulfur, due to the burning of coal in the process of generating electricity.

Q28: The dehydration of CH₃CH₂CH₂CH₂OH will give?
(a) HC≡ CCH₂CH₃
(b) CH₂≡ CH₂CH₃
(c) CH₃C≡ CCH₃
(d) CH₃CH=CHCH₃
Ans: (d)
An alkene is produced when dehydration of alcohol is performed in which alcohol, upon reaction with protic acids, loses a molecule of water to form alkenes.
Such a reaction is an elimination reaction.

Q29: When heat is absorbed during a chemical reaction, the reaction is said to be ___
(a) thermodynamic
(b) exothermic
(c) isothermal
(d) endothermic
Ans: (d)
An endothermic reaction is a chemical reaction in which heat is absorbed from its environment hence resulting in an increase in the enthalpy H of the system.

Q30: Which of the following best represents a solid gas mixture?
(a) milk
(b) kerosene
(c) soil
(d) smoke
Ans: (d)

Examples of solids in gas mixture:

• smoke
• ice clouds
• dust

Examples of liquid in gas mixture:

• fog
• mist
• vapour
• hair sprays

Examples of gas in solid mixture:

• aerogel
• styrofoam.

Q31: H⁺ + OH^- → HO
What does the equation above illustrate?
(a) precipitation
(b) hydration
(c) hydrolysis
(d) neutralization
Ans: (d)

• A neutralization reaction is a chemical reaction in which an acid and base react quantitatively to form salt and water as products.
• The reaction of an acid and a base to form water and a salt involves the combination of H+ ions and OH- ions to generate water.

Q32: Electrons enter into orbitals in order of increasing energy as exemplified by?
(a) 1S²2S²2PX²2py²2pz⁰3s⁰
(b) 1S²2S²2PX²2py¹2pz¹3s⁰
(c) 1S²2S²2PX¹2py¹2pz¹3s¹
(d) 1S²2S²2PX²2py²2pz⁰3s¹
Ans: (b)
Shells and subshells are filled in energy level order, so electrons will fill the 2p subshell before the 3s shell. And the x subshell before the y and z.

Q33: Wrought iron is obtained by heating cast iron in a furnace with?
(a) magnetite
(b) haematite
(c) carbon(ii)oxide
(d) calcium trioxosilicate(iv)
Ans: (b)
Cast iron + haematite = wrought iron

Q34: In the extraction of iron, hot air is introduced into the blast furnace through?
(a) valves
(b) open-hearths
(c) arcs
(d) tuyeres
Ans: (d)
Pre-heated air at about 600ºC is blown into the furnaces from the bottom through the tuyeres.

Q35: How many bonding pair are present in carbon(iv)oxide?
(a) 4
(b) 3
(c) 2
(d) 1
(a)
There are 4 bond pairs in CO₂ and no lone pairs are there.

Q36: 2-methylprop-1-ene is a structural isomer of?
(a)  But-1-yne
(b) 2-methyl But-1-ene
(c) 3-methyl prop-1-yne
(d)  But-2-ene
Ans: (d)
Isomers of Butene: are But-1-ene, But-2-ene, 2-Methylpropene or 2-methylprop-1-ene

Q37: Alkanes are used mainly?
(a) in the textile industry
(b) in the hydrogenation of oils
(c) as domestic and industrial fuels
(d) as fine chemicals
Ans: (c)
Alkanes are very useful as fuels.

Q38: What volume of (dm³) of water will be added to 10dm³ of 2.0 mol/dm³ HCL acid solution to give a final solution of 0.5 mol/dm³?
(a) 30
(b) 40
(c) 20
(d) 50
Ans: (b)
To make a fixed amount of a dilute solution from a stock solution,
use the formula: C₁V₁ = C₂V₂ 
where: V1 = Volume of stock solution needed to make the new solution.
C₁ = Concentration of stock solution.
V₂ = Final volume of new solution.
C₂ = Final  concentration of stock solution
2 x 10 = 0.5 x V₂
20 = 0.5V₂
20/0.5 = V₂
= 40dm³

Q39: The below table shows the compositions of the atmosphere of planet X. Which of these gases are present in higher percentages on earth?

(a) CO₂ and O₂
(b) N₂ and CO₂
(c) CO₂, O₂ and N₂
(d) O₂ and N₂
Ans: (d)
The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of other gases, too, such as carbon dioxide, neon, and hydrogen.

Q40: Hard water is water with high concentrations of dissolved ions, in particular calcium and
(a) magnesium ions
(b) nitrogen ions
(c) phosporus ions
(d) helium ions
(a)
Hard water is water with high concentrations of dissolved ions, in particular calcium and magnesium ions