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 431: On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as Options:
  A) efflorescence
  B) diliquescence
  C) hygroscopy
  D) hydrolysis
  Show Answer
  The correct answer is A .
• Question 432: Powdered marble reacts faster with hydrochloric acid solution than the granular form because the powdered form has Options:
  A) more molecules
  B) more atoms
  C) larger surface area
  D) relatively large mass
  Show Answer
  The correct answer is C .
• Question 433:

  PCl_5(g) ↔ PCl_3(g) + Cl_2(g)

  In the reaction above, a decrease in pressure will

  Options:
  A) Decelerate the reaction
  B) Increase the yield of PCl₃
  C) Increase the yield of PCl₅
  D) Accelerate the reaction
  Show Answer
  The correct answer is B .
• Question 434: In an electrochemical cell, polarization is caused by Options:
  A) chlorine
  B) oxygen
  C) tetaoxsulphate (Vl) acid
  D) hydrogen
  Show Answer
  The correct answer is D .
• Question 435: The carbon atoms on ethane are Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp⁴ hybridized
  D) sp hybridized
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  The correct answer is B .
• Question 436:

  A solution contains 20g of solute in 180g of solvent. If the solvent is water, what is the concentration of the solution in terms of mass by mass percentage

  Options:
  A) 11.%
  B) 22.2%
  C) 10%
  D) 20%
  Show Answer
  The correct answer is C .
• Question 437:

  The chlorinated alkane often used industrially to remove grease is?

  Options:
  A) Tetrachloromethane
  B) Chloromethane
  C) Trichloromethane
  D) Dichloromethane
  Show Answer
  The correct answer is A .
• Question 438: mE + nF → pG + qH. In the equation above, the equilibrium constant is given by? Options:
  A) (E)^m(F)ⁿ/ (G)ⁿ(H)^q
  B) (E)(F) / (G)(H)
  C) (G)^p(H)^q / (E)^m(F)ⁿ
  D) (G)(H) / (E)(F)
  Show Answer
  The correct answer is C .
• Question 439: In a neutralization reaction involving HCI and NaOH using litmus as indicator, the colour at the end point is Options:
  A) Blue
  B) Red
  C) Orange
  D) Purple
  Show Answer
  The correct answer is C .
• Question 440: The arrangement of particles in crystal lattices can be studied using Options:
  A) X-rays
  B) $\beta$-rays
  C) $\alpha$-rays
  D) $\gamma$-rays
  Show Answer
  The correct answer is A .