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 991: The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is Options:
  A) Na₂SO₄
  B) Na₂SO₃
  C) Na₂S
  D) Na₂CO₃
  Show Answer
  The correct answer is B .
• Question 992: What is the valence shell electron configuration of the element with atomic number 17? Options:
  A) 1s² 2s² 2p⁶ 3s² 3p⁴
  B) 1s² 2s² 2p⁶ 3s² 3p⁵
  C) 2s² 2p⁶
  D) 3s² 3p⁵
  Show Answer
  The correct answer is B .
• Question 993: Which of the following represent hybridization in ethyne? Options:
  A) Sp²
  B) Sp²d
  C) Sp³
  D) Sp
  Show Answer
  The correct answer is D .
• Question 994:

  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 995:

  The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?

  Options:
  A) carbon-14
  B) phosphorus-32
  C) cobalt
  D) iodine-131
  Show Answer
  The correct answer is C .
• Question 996: The electron configuration of two elements with similar chemical properties are represented by? Options:
  A) 1s²2s²2p⁵ and 1s²2s²2p⁴
  B) 1s²2s²2p⁴ and 1s²2s²2p⁶3s¹
  C) 1s²2s²2p⁶3s¹ and 1s²2s¹
  D) 1s²2s²2p⁴ and 1s²2s¹
  Show Answer
  The correct answer is C .
• Question 997: The reaction 3C(s) + 2Fe₂O₃(s) = 4Fe(s) + 3CO₂(g): $\mathrm{\Delta }$H =46.0 kJ is Options:
  A) isothermic
  B) adiabatic
  C) isobaric
  D) endothermic
  E) exothermic
  Show Answer
  The correct answer is D .
• Question 998: 5 block elements of the periodic table one made up of Options:
  A) groups 1, 2, 3
  B) groups 1, and 2
  C) group 3
  D) group 3 to 7
  Show Answer
  The correct answer is B .
• Question 999: Which of the following equilibria shows little or no net reaction when the volume of the system is decreased? Options:
  A) H_2(g) + I_2(g) ≈ 2HI_(g)
  B) 2NO₂^(g) ≈ N₂O_4(g)O_4(g)N₂O_4(g)
  C) PCI_5(g) ≈ PCI_3(g) + CI_2(g)
  D) ZnO_(s) + CO_2(g) ≈ ZnCO_3(g)
  Show Answer
  The correct answer is D .
• Question 1000: Bronze is an alloy of Options:
  A) copper, zinc and nickel
  B) aluminium and copper
  C) copper and zinc
  D) tin and zinc
  E) tin and copper
  Show Answer
  The correct answer is E .