JAMB CHEMISTRY 2021 LIKELY QUESTION

JAMB CHEMISTRY 2021 LIKELY QUESTION

1. The I.U.P.A.C name for the compoud
Cl
|
CH3 ——C ——-CH2 —–CH3
|
C
a. 2- chloro – FCCisotopentane
b. 3 – chloro – isopentane
c. 1 – chloro -2,2 -di methyl propane
d. 2 – chloro – 2 – ethylpropane

Answer: C

2. At S.T.P how many litres of hydrogen would be obtained from the reaction of 500cm³ of 0.5M H²SO4 with excess zinc metal ?
a. 22.4dm³ b. 11.2dm³ c.6.5dm³ d.0.025dm³

Answer: Zn + H²SO4 ————> ZnSO4 + H2
No. Of moles in 500cm³ = 0.5 × 500 / 1000 = 0.025 moles (d)

3. What reaction takes place when palm oil is added to potash and foams are observed ?
a. Neutralization b. Saponification
c. Esterification d. Salting out

Answers : Saponification (B)

4.Starch can be converted to ethyl alcohol by
A. distillation
B. fermentation ✔️
C. isomerization
D. cracking
E. cooking

5.When excess ethanol is heated to 145°c in the presence of concentrated sulphuric acid , the product is
A. diethyl ether ✔️
B. ethyne
C. diethyl sulphate
D. acetone
E. ethanoic acid

6.0.1 Faraday of electricity was passed through a solution of copper (II) sulphate. The maximum weight of copper deposited on the cathode would be ? ( Cu = 64)
A. 64.0g
B. 32.0g
C. 16.0g
D. 6.4g
E. 3.2g ✔️
SOLUTION : CUSO4 ——–> CU²+ SO²-4
CU²+ + 2e ——-> CU
1 Faraday will deposit 64/2 grams of copper
0.1 Faraday will deposit = 64/2 × 1/10 = 3.2grams

7.When heat is absorbed during a chemical reaction, the reaction is said to be
A. thermodynamic
B. exothermic
C. isothermal
D. endothermic ✔️
E. thermostatic

8.Two metallic ions associated with hard water are
A. Copper and Zinc
B. Magnesium and Silver
C. Calcium and Magnesium ✔️
D. Potassium and tin
E. Sodium and Lead

9.Which of the following raw materials would be required for the smelting of iron ore in a blast furnace ?
A. CaCO3 ✔️
B. Zn(NO³)²
C. CuSO4
D. AlCl3
E. CaSO4

10.Which of the following does not contain aluminum as a compound ?
A. Over head cables
B. Duralumin
C. Container for caustic soda
D. Container for nitric soda ✔️

11.The approximate volume of air containing 10cm³ of oxygen is ?
A. 20cm³
B. 25cm³
C. 50cm³ ✔️
D. 100cm³
E. 10cm³
SOLUTION : 1 volume of oxygen = 2 × 10
Volume of air = 100 × 10
100 × 10 / 20 = 50 cm³

12.Which of the following sulphides is insoluble In dilute Hcl?
A. Na²S
B. ZnS
C. CuS. ✔️
D. FeS
E. PbS

13.The characteristic reaction of carbonyl compounds is
A. Substitution
B. Elimination
C. Addition ✔️
D. Saponification
E. Fermentation

14.An example of polysaccharide is
A. -dextrose
B. Maltose
C. Glucose
D. Starch ✔️
E. Fructose

15.The shape of ammonia molecule is
A. Trigonal planar ✔️
B. Octahedral
C. Square planar
D. Tetrahedral

16.What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen ? [H=1 , O = 16 ]
A. 36.0g
B. 8.0g
C. 72.0g ✔️
D. 16.0g
E. 18.0g
SOLUTION : 2H² + O² ———-> 2H²O
From the equation
4g of Hydrogen produces 36g of water
8g of Hydrogen will produce Xg of water ( H20 )
>> 4g = 36g
8g = Xg. ( Cross multiply )
36 × 8 / 4. = 72g of H²O

17.What volume of oxygen is produced from the decomposition of 2moles of KClO3 at S.T.P ?
A. 22.4dm³
B. 33.6dm³
C. 44.8dm³
D. 67.2dm³ ✔️
E. 77.8dm³
SOLUTION : 1 MOLES OF OXYGEN OCCUPIED 22.4dm³
3MOLES OF OXYGEN OCCUPIED ( 3 × 22.4 )
= 67.2 DM

18.A carcinogenic substance is
A. Asbestos dust ✔️
B. Saw dust
C. Nitrogen (II) oxide
D. Carbon (II) oxide
E. Colloid

19. The electronic configuration of an element is 1s²2s²2p63p²3p³ . How many unpaired electrons are there in the element ?
A. 5
B. 4
C. 3 ✔️
D. 2

20. Which of the following is arranged in order of increasing electronegativity ?
A. Chlorine , aluminum , magnesium , phosphorus , sodium
B. Sodium , magnesium, aluminum, phosphorus , chlorine ✔️
C. Chlorine, phosphorus , aluminum , magnesium , sodium
D. Sodium , chlorine , phosphorus , magnesium , aluminum

21.How many grams of bromine will be required to completely react with 10g of propyne ?[ C = 12 , H = 1 , Br =80]
A. 20g
B. 40g
C. 60g
D. 80g ✔️

Solution
C³H⁴ + 2Br² ————> CHBr²CBr²CH³
Propyne + Bromine
Propyne = 12×3 + 1×4 = 36+4 = 40g of propyne ( C³H⁴ )
Bromine = 2 [ 80 × 2 ] = 2 [160 ] = 320g of Bromine ( 2Br² )

.°. 40g of propyne reacts with 320g of Bromine
10g of propyne reacts with = 10×320 / 40 = 80g (D)

22.The characteristics reaction of carbonyl compounds is
A. Substitution
B. Elimination
C. Addition ✔️
D. Saponification

23.An example of polysaccharide is
A. -dextrose
B. Mannose
C. Glucose
D. Starch ✔️

24.Water has a rather high boiling point despite its low molecular mass because of the presence of
A. Hydrogen bonding✔️
B. Covalent bonding
C. Ionic bonding
D. Metallic bond

25.Which of the following compounds is a base ?
A. Co²
B. CaO ✔️
C. H³PO³
D. CH³COOCH³

26.. A solid that absorbs water from the atmosphere and forms an aqueous solution is
A. Hydrophilic
B. Efflorescent
C. Deliquescent ✔️
D. Hydroscopic

27.The most abundant element on the earths crust is
A. Nitrogen
B. Hydrogen
C. Oxygen ✔️
D. Fluorine

28.. The most suitable metal that can be used as lightning conductor is
A. Silver
B. Copper ✔️
C. Iron
D. Aluminum

29. Metalliods are also referred to as
A. Semi metal ✔️
B. Metals
C. Colloids
D. Non – metals

30.Zinc and carbon rods are used as anode and cathode respectively in a
A. Leclanche cell ✔️
B. Lead accumulator
C. Daniel cell
D. Voltaic cell

31.The basicity of CH³COOH is
A. 1 ✔️
B. 2
C. 3
D. 4

32.Coffee stains can be removed by
A. Kerosene
B. Turpentine
C. A solution of borax in water
D. Ammonia solution ✔️

33.Which of the following is used as fuel in miners lamp ?
A. Ethanal
B. Ethyne ✔️
C. Ethene
D. Ethane

34.Which of the following is used to hasten the ripening of fruits ?
A. Ethene ✔️
B. Ethanol
C. Ethyne
D. Ethane

35.The ability of carbon to form long chains is referred to as
A. Alkylation
B. Acylation
C. Catenation ✔️
D. Carbonation

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