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 451:

  A solution X, on mixing with AgNO${}_3$ solution gives a white precipitate soluble in aqueous NH${}_3$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

  Options:
  A) Al${}^{3+}$, Cl${}^{-}$
  B) Hg${}^{+}$, SO${}_4^{2-}$
  C) Pb${}^{2+}$, Cl${}^{-}$
  D) Ag${}^{+}$, SO${}_4^{2-}$
  Show Answer
  The correct answer is C .
• Question 452:

  

  The diagram above shows the reaction path of an exothermic reaction. The heat of reaction is represented by

  Options:
  A) l
  B) ll
  C) lll
  D) lV
  Show Answer
  The correct answer is D .
• Question 453: What is the concentration of H⁺ ions in moles per dm³ of a sodium of pH 4.398? Options:
  A) 4.0 χ 10^-5
  B) 0.4 χ 10^-5
  C) 4.0 χ 10^-3
  D) 0.4 χ 10^-3
  Show Answer
  The correct answer is A .
• Question 454: 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 455: The gas that is used for the treatment of cancer is Options:
  A) Neon
  B) Radon
  C) Xenon
  D) Argon
  Show Answer
  The correct answer is B .
• Question 456: The product formed at the the cathode during the electrolysis of sodium chloride solution with carbon electrodes is? Options:
  A) sodium
  B) chlorine
  C) hydrogen
  D) sodium hydroxide
  E) oxygen
  Show Answer
  The correct answer is C .
• Question 457: What volume of 0.5mldm³ H₂SO₄ will exactly neutralize 20cm³ of 0.1moldm³ NaOH Solution? Options:
  A) 2.0cm³
  B) 5.0cm³
  C) 6.8cm³
  D) 8.3cm³
  Show Answer
  The correct answer is A .
• Question 458:

  

  The IUPAC name for

  Options:
  A) 2-methylbutanoic acid
  B) 2-methyl-1- hydroxyketone
  C) 2-methyl-1-hydroxy aldehyde
  D) 2-methylpentanoic acid
  Show Answer
  The correct answer is A .
• Question 459:

  Which of the following is a common laboratory indicator for bases?

  Options:
  A) Methyl orange
  B) Phenolphthalein
  C) Bromothymol blue
  D) Litmus
  Show Answer
  The correct answer is B .
• Question 460: A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The sample contains Options:
  A) Cl^-
  B) NO₃^-
  C) SO₃^2-
  D) SO₄^2-
  Show Answer
  The correct answer is C .