Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 1381: One mole of hydrocarbon contains 6g of hydrogen. If the molecular weight is 54, the hydrocarbon is an? Options:
  A) alkanone
  B) alkane
  C) alkene
  D) alkyne
  Show Answer
  The correct answer is D .
• Question 1382: 0.1 Faraday of electricity was passed through a solution of copper (ll) sulphate. The maximum weight of copper deposited on the cathode would be [Cu = 64] Options:
  A) 64.0g
  B) 32.0g
  C) 16.0g
  D) 6.4 g
  E) 3.2g
  Show Answer
  The correct answer is E .
• Question 1383: Which of the following compounds will impart a brick-red colour to a non-luminious bunsen flame? Options:
  A) NaCl
  B) LiCl
  C) CaCl₂
  D) MgCl₂
  Show Answer
  The correct answer is C .
• Question 1384:

  A radioactive nucleus has a half-life of 20 years, starting with 100,000 particles, how many particles will be left exactly at the end of 40 years

  Options:
  A) 75,000 particles
  B) 35,000 particles
  C) 25,000 particles
  D) 50,000 particles
  Show Answer
  The correct answer is C .
• Question 1385: The general formula of alkanones is Options:
  A) RCHO
  B) R₂CO
  C) RCOOH
  D) RCOOR
  Show Answer
  The correct answer is B .
• Question 1386: 20.00 cm ³ of a solution containing 0.53 g of anhydrous Na₂CO₃ in 100 cm³ requires 25.00 cm³ of H₂SO₄ for complete neutralisation. The concentration of the acid solution in moles per dm is [H =1, C = 12, O = 16, Na =23, S = 32] Options:
  A) 0.02
  B) 0.04
  C) 0.06
  D) 0.08
  Show Answer
  The correct answer is B .
• Question 1387:

  

  In the experiment above, a current was passed for 10 minutes and 0.63g of copper was found to be deposited on the cathode of CuSO₄ cells. The weight of silver deposited on the cathode og AgNO³ cell during the same period would be? [Cu = 63, Ag = 108]

  Options:
  A) 0.54g
  B) 1.08g
  C) 1.62g
  D) 2.16g
  E) 3.24g
  Show Answer
  The correct answer is B .
• Question 1388: Water is poured over a white solid and a colourless neutral gas is evolved which burns with a sooty flame. The white solid is? Options:
  A) calcium
  B) calcium oxide
  C) calcium carbide
  D) sodium peroxide
  E) sodium sulphate
  Show Answer
  The correct answer is C .
• Question 1389: In the laboratory preparation of trioxonitrate (V) acid the nitrogen(iv) oxide formed as a by-product is removed by Options:
  A) further heating
  B) adding concentrated H₂SO₄
  C) cooling the acid solution with cold water
  D) bubbling air through the acid solution
  Show Answer
  The correct answer is D .
• Question 1390: What is the partial pressure of hydrogen gas collected over water at standard atmospheric pressure and 25^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature? Options:
  A) 737 mm Hg
  B) 763 mm Hg
  C) 777 mm Hg
  D) 783 mm Hg
  Show Answer
  The correct answer is A .