JAMB 2020 past questions

Checked by the Skolra question team · Last updated 23 October 2026

We hold 508 questions from the 2020 JAMB papers in 11 subjects, each with the answer and an explanation. Below are ten of them, from ten subjects, and then every 2020 paper we hold.

Ten JAMB 2020 questions with answers

From the Mathematics paper
1.
The chord ST of a circle is equal to the radius r of the circle. Find the length of arc ST
1. A
  πr/2
2. B
  πr/3
  Correct
3. C
  2πr/3
4. D
  πr/6
Show answerHide answer
Answer: B
Setting up the triangle: Join the two ends of the chord S and T to the centre O of the circle. OS = OT = r (radii), and we are told ST = r too. So triangle OST has all three sides equal to r — it is an equilateral triangle.
Every angle in an equilateral triangle is 60°, so the angle at the centre, angle SOT = 60° = π/3 radians.
Arc length formula: Arc length = rθ, where θ is the central angle in radians.
Arc ST = r × π/3 = πr/3.
From the Physics paper
2.
A transformer has 300 turns of wire in the primary coil and 30 turns in the secondary coil. If the input voltage is 100 volts, the output voltage is
1. A
  30 V
2. B
  3 V
3. C
  1000 V
4. D
  10 V
  Correct
Show answerHide answer
Answer: D
For a transformer, the ratio of secondary to primary voltage equals the ratio of secondary to primary turns:
V_s/V_p = N_s/N_p
Given N_p = 300 turns, N_s = 30 turns, V_p = 100 V:
V_s = V_p × (N_s/N_p) = 100 × (30/300) = 100 × 0.1 = 10 V
Since the secondary coil has fewer turns than the primary (30 against 300), this is a step-down transformer, so the output voltage must be smaller than the input voltage — 10 V is correct.
From the Chemistry paper
3.
A gaseous metallic chloride MCl consists of 20.22% of M by mass. The formula of the chloride is?
[ M = 27, Cl = 35.5]
1. A
  MCl4
2. B
  MCl
3. C
  MCl2
4. D
  MCl3
  Correct
Show answerHide answer
Answer: D
Let the chloride have formula MCl_n. Percentage of M by mass:
%M = M / (M + 35.5n) × 100 = 20.22%
With M = 27 (the atomic mass given for the metal):
27 / (27 + 35.5n) = 0.2022
27 = 0.2022(27 + 35.5n)
27 = 5.4594 + 7.1781n
21.5406 = 7.1781n
n ≈ 3
So the metal combines with three chlorine atoms, giving MCl3 as the correct formula.
Candidates who pick MCl2 or MCl4 usually round the division carelessly or mis-multiply 0.2022 by 35.5 instead of solving the full equation. Picking MCl comes from ignoring the percentage entirely and just matching the stated formula "MCl" in the question, forgetting that the "M" in "MCl" is a general placeholder, not the actual subscript.
From the Biology paper
4.
Which of the following waste products in plants is excreted through the stomata and lenticles?
1. A
  Water vapour and mineral salts
2. B
  Carbon (IV) oxide and oxygen
  Correct
3. C
  Nitrogenous wastes and latex
4. D
  Tannins and resins
Show answerHide answer
Answer: B
Carbon (IV) oxide and oxygen are the waste (by-product) gases of respiration and photosynthesis in plants, and they are excreted through the stomata (in the leaves) and the lenticels (in the woody stem), which are the pores that allow gaseous exchange with the atmosphere.
The other options name real plant waste products, but they leave the plant through different routes, not the stomata/lenticels:
Water vapour is indeed lost through the stomata during transpiration, but the mineral salts paired with it here are not excreted that way — excess mineral salts and water are more associated with guttation through hydathodes and with the roots, so this pairing is wrong.
From the Government paper
5.
Africans were first elected to the legislative council in British West Africa in _________
1. A
  1900
2. B
  1925
  Correct
3. C
  1910
4. D
  1935
Show answerHide answer
Answer: B
Africans were first elected to the legislative council in British West Africa in 1925. This was a significant step toward self-governance, though Africans remained a minority in the council. The Clifford Constitution of 1922 provided for the election of Africans to the Lagos and other legislative councils.
From the Economics paper
6.
In order to raise more revenue for a certain period, the government should impose higher taxes on goods whose demand
1. A
  is elastic, so customers easily switch to alternatives
2. B
  changes rapidly with consumer preferences
3. C
  is unitary elastic, balancing tax and quantity
4. D
  is inelastic, so quantity demanded changes little with price
  Correct
Show answerHide answer
Answer: D
To raise more revenue from taxation, governments should tax goods with inelastic demand. When demand is inelastic, quantity demanded doesn't decrease much despite the higher tax, so total tax revenue increases.
From the Commerce paper
7.
Freight note is a document
1. A
  Proof of payment for goods
2. B
  Issued by the importer
3. C
  Issued by the transport company to the consignor
  Correct
4. D
  Receipt of goods at destination
Show answerHide answer
Answer: C
A freight note is a transport document issued by the carrier/transport company to acknowledge receipt of goods and details of shipment terms.
From the Principles of Accounts paper
8.
A major cause of discrepancy between the bank statement and the cashbook that overstates the bank statement balance is the
1. A
  dishonoured cheque returned unpaid by the bank
2. B
  cheques paid in but not yet credited by the bank
3. C
  cheques drawn but not yet presented for payment
  Correct
4. D
  bank charges and commission debited by the bank
Show answerHide answer
Answer: C
The question is asking for the item that makes the bank statement balance higher than the cash book balance. So for each item you must ask: who has recorded it already, the trader or the bank?
When the business issues a cheque to a supplier, it immediately credits (reduces) the cash book. But until that supplier walks into the bank with the cheque, the bank knows nothing about it and has not paid out the money. So the bank still shows the higher figure. That is why cheques drawn but not yet presented for payment (unpresented cheques) overstate the bank statement balance, and in the reconciliation statement they are the item you deduct when starting from the bank statement balance.
From the Agricultural Science paper
9.
Which of the following is not a breed of cattle?
1. A
  N'dama
2. B
  White Fulani
3. C
  Sokoto Gudali
4. D
  Yankasa
  Correct
Show answerHide answer
Answer: D
White Fulani, N'dama and Sokoto Gudali are all well-known cattle breeds in Nigeria. Yankasa is a breed of sheep, not cattle.
From the History paper
10.
North Africa according to United Nation Classification comprises of how many countries.
1. A
  7
  Correct
2. B
  9
3. C
  5
4. D
  12
Show answerHide answer
Answer: A
According to the United Nations geoscheme for Africa, Northern Africa comprises seven countries: Algeria, Egypt, Libya, Mauritania, Morocco, Sudan, and Tunisia. Western Sahara is also sometimes listed as a territory within the sub-region but it is not a fully recognised UN member state. These countries are characterised by their position along the Mediterranean coast and in the Sahara Desert, their predominantly Arabic-speaking populations, and their historical ties to trans-Saharan and Mediterranean trade.

The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check

Spotted a wrong answer? Tell us from the app or on the contact page and we check it.

Practise every 2020 JAMB paper in the Skolra app

All 508 questions, each with the answer and an explanation, on a timed CBT screen.

Download for Windows Download for Mac

About the app · Skolra for Windows · Skolra for Mac

The 2020 JAMB papers we hold

Each paper has its own page with ten questions and answers.

The 2020 JAMB papers and the questions we hold from each
Subject	Questions we hold
Mathematics	40
Physics	38
Chemistry	38
Biology	35
Government	40
Economics	39
Commerce	40
Principles of Accounts	39
Agricultural Science	79
History	80
Home Economics	40

Other years

All JAMB past questions, by subject