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 631: Which of the following metals will liberate hydrogen from steam or dilute acid? Options:
  A) Copper
  B) Iron
  C) Lead
  D) Mercury
  Show Answer
  The correct answer is B .
• Question 632:
  

  Use the section of the periodic table above to answer this question.

  Which letter represents a non-metal that is a solid at room temperature?

  Options:
  A) T
  B) R
  C) J
  D) X
  Show Answer
  The correct answer is A .
• Question 633:

  The electronic configuration of element Z is 1s${}^2$ 2s${}^2$ 2p${}^6$ 3s${}^2$ 3p${}^1$. What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion.

  Options:
  A) Z${}_3$(SO${}_4$)${}_2$
  B) ZSO${}_4$
  C) Z${}_2$ SO${}_4$
  D) Z${}_2$(SO${}_4$)${}_3$
  Show Answer
  The correct answer is D .
• Question 634:

  Consider the equation below:

  Cr${}_2$O${}_7^{2-}$ + 6Fe${}^{2+}$ + 14H${}^{+}$ $\to$ 2Cr${}^{3+}$ + 6Fe${}^{3+}$ + 7H${}_2$O.

  The oxidation number of chromium changes from

  Options:
  A) +5 to +3
  B) +6 to +3
  C) -2 to +3
  D) +7 to +3
  Show Answer
  The correct answer is B .
• Question 635: Hydrogen is used in oxy-hydrogen flames for melting metals because it Options:
  A) evolves a lot of heat when burnt
  B) combines explosively with oxygen
  C) is a very light gas
  D) is a rocket fuel
  Show Answer
  The correct answer is A .
• Question 636:

  200cm${}^3$ of 0.50mol/dm${}^3$ solution of calcium hydrogen trioxocarbonate (IV) is heated. The maximum weight of solid precipitated is

  Options:
  A) 10g
  B) 25g
  C) 20g
  D) 15g
  Show Answer
  The correct answer is A .
• Question 637:

  The IUPAC nomenclature of the compound

  H${}_3$C - CH(CH${}_3$) - CH(CH${}_3$) - CH${}_2$ - CH${}_3$

  Options:
  A) 3,4- dimethylhexane
  B) 2,3- dimethyl pentane
  C) 2- ethyl hexane
  D) 2,3- dimethylhexane
  Show Answer
  The correct answer is B .
• Question 638:

  Which of the following is the electronic configuration of sodium?

  (Atomic number of Na = 11)

  Options:
  A) 1s² 2s²2p⁶ 3s²
  B) 1s² 2s²2p⁶ 3s² 3p1s² 2s²2p⁶ 3s¹
  C) 1s² 2s²2p⁶ 3s¹
  D) 1s² 2s²2p⁶ 3s^°
  E) 1s² 2s²2p⁶ 4s¹
  Show Answer
  The correct answer is C .
• Question 639: A change in the temperature of a saturated solution disturbs the equilibrium between the Options:
  A) Undissolved solute and the solvent
  B) Dissolved solute and the solvent
  C) Dissolved solute and the undissolved solute
  D) Dissolved solute and the solution
  Show Answer
  The correct answer is C .
• Question 640:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  The molecular formula of X is

  Options:
  A) C₁₂H₂₂O₁₁
  B) C₆H₁₂O₆
  C) C₃H₆O ₃
  D) C₇H₁₄O₇
  E) C₁₂H₆O₄
  Show Answer
  The correct answer is B .