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DAY 3 CHEMISTRY JAMB QUESTIONS

Electrolysis

1. During electrolysis, oxidation occurs at the:
A) Anode
B) Cathode
C) Electrolyte
D) Salt bridge

Answer: A) Anode

2. The electrolyte used in the electrolysis of brine is:
A) Sodium chloride solution
B) Copper(II) sulfate solution
C) Distilled water
D) Lead(II) nitrate solution

Answer: A) Sodium chloride solution

3. Which of the following gases is liberated at the anode during the electrolysis of brine?
A) Hydrogen
B) Oxygen
C) Chlorine
D) Nitrogen

Answer: C) Chlorine

Organic Chemistry (about 40%)

4. Alkanes are generally known as:
A) Saturated hydrocarbons
B) Unsaturated hydrocarbons
C) Aromatic compounds
D) Alcohols

Answer: A) Saturated hydrocarbons

5. The general formula of alkanes is:
A) C_nH_{2n}
B) C_nH_{2n+2}
C) C_nH_{2n-2}
D) C_nH_n

Answer: B) C_nH_{2n+2}

6. Ethene is an example of a/an:
A) Alkane
B) Alkene
C) Alkyne
D) Alcohol

Answer: B) Alkene

7. Which of the following is used in the industrial preparation of ethanol?
A) Fermentation of sugars
B) Electrolysis of water
C) Burning of hydrocarbons
D) Reaction of acids

Answer: A) Fermentation of sugars

8. Which of the following is an alkyne?
A) Methane
B) Ethene
C) Ethyne
D) Ethanol

Answer: C) Ethyne

9. The functional group of alcohols is:
A) –COOH
B) –OH
C) –CHO
D) –C≡C–

Answer: B) –OH

10. Which of the following compounds is an aromatic hydrocarbon?
A) Ethene
B) Benzene
C) Ethyne
D) Methane

Answer: B) Benzene

11. Boyle’s law states that at constant temperature, the pressure of a gas is:
A) Directly proportional to volume
B) Inversely proportional to volume
C) Directly proportional to temperature
D) Constant

Answer: B) Inversely proportional to volume

12. Charles’ Law states that:
A) Pressure is constant when volume changes
B) Volume is directly proportional to absolute temperature
C) Volume is inversely proportional to temperature
D) Temperature is inversely proportional to pressure

Answer: B) Volume is directly proportional to absolute temperature

13. Avogadro’s law states that equal volumes of gases under the same conditions contain:
A) Equal masses
B) Equal number of molecules
C) Equal densities
D) Equal pressure

Answer: B) Equal number of molecules

14. The electronic configuration of sodium is:
A) 2, 8, 8
B) 2, 8, 1
C) 2, 1, 8
D) 8, 8, 2

Answer: B) 2, 8, 1

15. How many electrons are in the outermost shell of an oxygen atom?
A) 2
B) 4
C) 6
D) 8

Answer: C) 6

Preparation of Compounds

16. Oxygen gas can be prepared in the laboratory by heating:
A) Sodium chloride
B) Potassium trioxochlorate(V)
C) Calcium carbonate
D) Ammonium chloride

Answer: B) Potassium trioxochlorate(V)

17. Hydrogen gas can be prepared by the action of dilute HCl on:
A) Copper
B) Sodium
C) Zinc
D) Carbon

Answer: C) Zinc

Half-Life

18. The half-life of a radioactive element is 2 hours. How much of a 20g sample remains after 6 hours?
A) 10g
B) 5g
C) 2.5g
D) 1.25g

Answer: C) 2.5g
(Solution: After each 2 hours → half. 20g → 10g → 5g → 2.5g)

19. The time required for half the nuclei of a radioactive sample to decay is called:
A) Decay time
B) Rate of decay
C) Half-life
D) Reaction time

Answer: C) Half-life

20. If a substance has a half-life of 3 minutes, how much of a 16g sample will remain after 9 minutes?
A) 8g
B) 4g
C) 2g
D) 1g

Answer: D) 2g
(Solution: 16g → 8g → 4g → 2g

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