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 2081:

  

  The IUPAC name of the compound above is
  Options:
  A) 2,2-dimethyl but -1-yne
  B) 2,2-dmethyl but -1-ene
  C) 3,3-dimethyl but -1-ene
  D) 3,3-dimethyl but-1-yne
  Show Answer
  The correct answer is C .
• Question 2082: If 30cm³ of oxygen diffuses through a porous pot in 7 seconds, how long will it take 60cm³ of chlorine to diffuse through the same pot, if the vapour densities of oxygen and chlorine are 16 and 36 respectively? Options:
  A) 9.3 sec
  B) 14 sec
  C) 21 sec
  D) 28 sec
  E) 30.3 sec
  Show Answer
  The correct answer is C .
• Question 2083: The process of converting starch to ethanol is Options:
  A) cracking
  B) distillation
  C) fermentation
  D) oxidation
  Show Answer
  The correct answer is C .
• Question 2084: The alkyl group is represented by the general formula Options:
  A) C_nH₂n
  B) C_nH₂n − 2
  C) C_nH₂n + 1
  D) C_nH₂n + 2
  Show Answer
  The correct answer is C .
• Question 2085:

  What is the mass percentage of carbon (C) in methane (CH4)? (The molar mass of carbon is approximately 12 g/mol.)

  Options:
  A) 25%
  B) 12%
  C) 75%
  D) 50%
  Show Answer
  The correct answer is C .
• Question 2086: 25cm³ of a 0.2 mol dm³ solution of Na₂CO₃ requires 20 cm³ of a solution of HCl for neutralization. The concentration of the HCl solution is Options:
  A) 0.5 mol dm³
  B) 0.6 mol dm³
  C) 0.2 mol dm³
  D) 0.4 mol dm³
  Show Answer
  The correct answer is A .
• Question 2087:

  Which of the following are chemical changes?

  I. cooking of food
  II. digestion of food
  III. freezing of water
  IV. water is heated up

  Options:
  A) I and II
  B) I, II, and III
  C) III and IV
  D) all of the above
  Show Answer
  The correct answer is A .
• Question 2088: If the change in free energy of a system is -899 Jmol^-1 and the entropy change is 10Jmol^-1k^-1 at 250C, calculate the enthalpy change. Options:
  A) +2081 Jmol^-1
  B) -2081 Jmol^-1
  C) -649 Jmol^-1
  D) +649 Jmol^-1
  Show Answer
  The correct answer is A .
• Question 2089:

  

  The name of the compound above is

  Options:
  A) acetic acid
  B) propanal
  C) propanol
  D) ethanoic acid
  E) propanoic acid
  Show Answer
  The correct answer is E .
• Question 2090:

  

  Which of the structural forms above is ethanoic acid is

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is E .