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 181: Moving from left to right across a period, the general rise in the first ionization energy can be attributed to the Options:
  A) decrease in nuclear charge
  B) increase in nuclear charge
  C) decrease in screening effect
  D) increase in screening effect
  Show Answer
  The correct answer is B .
• Question 182:

  Beryllium and Aluminium have similar properties because they

  Options:
  A) are both metals
  B) belong to the same group
  C) belong to the same period
  D) are positioned diagonally to each other
  Show Answer
  The correct answer is D .
• Question 183:

  Addition of charcoal to the filter bed of sand during water treatment for township supply is to?

  Options:
  A) prevent goiter
  B) prevent tooth decay
  C) remove odour
  D) kill germs
  Show Answer
  The correct answer is C .
• Question 184: When sugar is dissolved in tea, the reaction is always accomplished by Options:
  A) positive change
  B) negative entropy change
  C) no entropy change
  D) a minimum entropy change
  Show Answer
  The correct answer is C .
• Question 185:

  

  2HCI_(ag) + CaCO_{3(s) → CaCl2(s)} + CO _2(g) +H₂O₍₁₎

  From the reaction above, which of the curves in the diagram represents the production of carbon (IV) oxide as dilute HCI is added?

  Options:
  A) L
  B) M
  C) N
  D) P
  Show Answer
  The correct answer is B .
• Question 186: For a general equation of the nature xP + yQ ≈ mR + nS, the expression for the equilibrium constant is? Options:
  A) k (p)^x (Q)^y
  B) (p)^x (Q)^y / (R)^m (S)ⁿ
  C) (R)^m (S)ⁿ / (p)^x (Q)^y
  D) m(R) n (S) / x(P) y (Q)
  Show Answer
  The correct answer is C .
• Question 187: Millikan's contributions to the development of atomic theory is the determination of Options:
  A) charge on electron
  B) positive rays
  C) charge to mass ratio
  D) cathode rays
  Show Answer
  The correct answer is A .
• Question 188:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100°C, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0°C?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 189: The decolourization of purple colour of tetraoxomanganate (VII) ion is a test for Options:
  A) alkenes
  B) alkanols
  C) alkanals
  D) alkanes
  Show Answer
  The correct answer is A .
• Question 190:

  A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?

  [K = 39, Cl = 35.5, O = 16]

  Options:
  A) KClO₄
  B) KClO
  C) KClO₂
  D) KClO₃
  Show Answer
  The correct answer is D .