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 461:

  A correct electrochemical series can be obtained from Na, Ca, Al, Mg, Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging

  Options:
  A) Al and Mg
  B) Zn and Fe
  C) Zn and Pb
  D) Pb and H
  Show Answer
  The correct answer is A .
• Question 462: The standard enthalpies of formation of CO_2(g), H₂O(g) and CO_(g) in kJ mol^- are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO_(g) + H_2(g)O → CO_2(g) + H_2(g)? Options:
  A) -42 KJ mol^-
  B) +42 KJ mol^-
  C) -262 KJ mol^-
  D) +262 KJ mol^-
  Show Answer
  The correct answer is A .
• Question 463:

  

  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 464:

  10g of a solid is in equilibrium with its own vapour.

  When 1 g of a small amount of solid is added, the vapour pressure?

  Options:
  A) remains the same
  B) drops
  C) increases by 1%
  D) increases by 99%
  Show Answer
  The correct answer is B .
• Question 465: How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80) Options:
  A) 4. 1 g
  B) 6. 1 g
  C) 8. 1g
  D) 16.2g
  Show Answer
  The correct answer is C .
• Question 466: In the industrial production of H₂ from natural gas the CO₂ produced along with the H₂ is removed by Options:
  A) washing under pressure
  B) drying over phosphorus (V) oxide
  C) passing the mixture into lime water
  D) using ammonical copper (I) chloride
  Show Answer
  The correct answer is A .
• Question 467:

  56.00cm³ of a gas at S.T.P. weighed 0.11g. What is the vapour density of the gas?
  [Molar volume of a gas at S.T.P = 22.4dm³]

  Options:
  A) 11.00
  B) 22.00
  C) 33.00
  D) 44.00
  Show Answer
  The correct answer is B .
• Question 468: Two organic compounds K and L were treated with a few drops of Fehling's solutions respectively . K formed a brick-red precipitate while L, remains unaffected. The compound K is an Options:
  A) alkanol
  B) alkane
  C) alkanal
  D) alkanone
  Show Answer
  The correct answer is C .
• Question 469:

  2Na ₂ O _2(s) + 2H ₂ O ₂₍₁₎ → 4 NaOH_(s) +O_2(s)

  The substance that is oxidized in the reaction above is

  Options:
  A) 2NaO_2(s)
  B) NaOH(aq)
  C) H₂O₍₁₎
  D) O_2(g)
  Show Answer
  The correct answer is A .
• Question 470:

  I. H = 1s¹ II. N = 1s² 2s² p³ III. O = 1s² 2s² p⁴ IV. Zn = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰

  From the above, which of the following pairs is like to be paramagnetic?

  Options:
  A) I and II
  B) I and III
  C) I and IV
  D) III and IV
  Show Answer
  The correct answer is A .