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 471:

  For the reaction NH₄NO₂ $\to$ N₂ + 2H₂O, calculate the volume of nitrogen that would be produced at S. T. P from 320 g of the dioxonitrate(iii)salt. (Relative atomic masses: N = 14, O = 16, H = 1)

  Options:
  A) 2.24 dm ³
  B) 224 dm³
  C) 1.12 dm ³
  D) 112 dm ³
  E) 4.48 dm ³
  Show Answer
  The correct answer is D .
• Question 472: Calculate the number of moles of HCl present in 20cm³ of a 0.75M solution of the acid Options:
  A) 0.015 mole
  B) 0.038 mole
  C) 3.800 moles
  D) 1.500 moles
  Show Answer
  The correct answer is A .
• Question 473: A supersaturated solution is said to contain Options:
  A) more solute than it can dissolve at that temperature in the presence of undissolved solute
  B) as much solute as it can dissolve at that temperature in the presence of undissolved solute
  C) as much solute as it can dissolve at that temperature
  D) more solute than it can dissolve at that temperature
  Show Answer
  The correct answer is D .
• Question 474:

  The heat required to raise the temperature of the body by 1k is called?

  Options:
  A) Specific heat
  B) Thermal capacity
  C) Water equivalent
  D) None of the above
  Show Answer
  The correct answer is B .
• Question 475:

  An organic functional group which can likely decolorize ammoniacal silver nitrate is?

  Options:
  A) alkene
  B) alkane
  C) alkyne
  D) alkanol
  Show Answer
  The correct answer is C .
• Question 476: Which of the following reaction is endothermic? Options:
  A) C_(s) + O_2(g) → CO_2(g)
  B) CaO_(s) + H₂O_(l) → Ca(OH)_2(s)
  C) C_(s) + H₂O_(g) → CO_(g) + H_2(g)
  D) HCl_(aq) + NaOH_(aq) → NaCl_(aq) + H₂O_(l)
  Show Answer
  The correct answer is C .
• Question 477:

  In electrovalency, the oxidation number of the participating metal is always

  Options:
  A) decreasing
  B) increasing
  C) constant
  D) neutral
  Show Answer
  The correct answer is C .
• Question 478: The bleaching action of chlorine gas is effective due to the presence of Options:
  A) hydrogen chloride
  B) water
  C) air
  D) oxygen
  Show Answer
  The correct answer is B .
• Question 479: In the electrolytic extraction of aluminum, the function of the molten cryolite is to Options:
  A) precipitate aluminium hdroxide
  B) lower the melting point of aluminium oxide
  C) act as a raw materials
  D) act as a solvent
  Show Answer
  The correct answer is B .
• Question 480: As the concentration of an electrolyte reduces, the conductivity Options:
  A) reduces to zero
  B) decreases
  C) increase
  D) is unaffected
  Show Answer
  The correct answer is C .