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 571: The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is Options:
  A) carbon-14
  B) phosphorus-32
  C) cobalt-60
  D) iodine-131
  Show Answer
  The correct answer is C .
• Question 572:

  A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as __________.

  Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 573: Magnesium (IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to? Options:
  A) increase the surface area of the reactants
  B) increase the concntration of the reactants
  C) lower the activation energy for the reaction
  D) lower the heat of reaction, ∆H, for the reaction
  Show Answer
  The correct answer is C .
• Question 574:

  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 .
• Question 575: Which of the following acts as both a reducing and an oxidizing agent? Options:
  A) H₂
  B) SO₂
  C) H₂S
  D) C
  Show Answer
  The correct answer is B .
• Question 576: Environmental pollution is worsened by the release from the automobile exhaust of Options:
  A) water vapour
  B) steam
  C) smoke
  D) heavy metals
  E) steam and smoke
  Show Answer
  The correct answer is D .
• Question 577: Certain useful waxes are composed mainly of Options:
  A) amino acids
  B) glycerols
  C) alkanols
  D) alkanoates
  Show Answer
  The correct answer is B .
• Question 578: The knowledge of half-life can be used to Options:
  A) create an element
  B) detect an element
  C) spilt an element
  D) irradiate an element
  Show Answer
  The correct answer is B .
• Question 579: When dilute hydrochloric acid is added to iron(ll)sulphide, the gas evolved will? Options:
  A) turn moist red litmus paper blue
  B) turn lime water milky
  C) blacken lead acurate paper
  D) rekindle a glowing splint
  E) burn a sqeakly pop
  Show Answer
  The correct answer is C .
• Question 580:

  

  The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. At room temperature (300 K)

  Options:
  A) Y is twice as soluble as X
  B) X is twice as soluble as Y
  C) X and Y are soluble to the same extent
  D) X is three times as soluble as Y
  E) Y is three times as soluble as X
  Show Answer
  The correct answer is A .