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 851: The soft solder used for welding and plumbing is alloy of Options:
  A) lead and tin
  B) iron and tin
  C) lead and zinc
  D) iron and zinc
  Show Answer
  The correct answer is A .
• Question 852: An example of a solid emulsion is Options:
  A) Butter
  B) Hair cream
  C) Milk
  D) Cod-liver oil
  Show Answer
  The correct answer is A .
• Question 853: When salt loses its water of crystallization to the atmosphere on exposure, the process is said to be Options:
  A) efflorescence
  B) déliquescence
  C) effervescence
  D) fluorescence
  Show Answer
  The correct answer is A .
• Question 854: An isotope has an atomic number of 15 and a mass number of 31. The number of proton it contains is Options:
  A) 16
  B) 15
  C) 31
  D) 46
  Show Answer
  The correct answer is B .
• Question 855: Hydrogen is readily released when dilute hydrochloric acid reacts with Options:
  A) Cu
  B) Na
  C) Au
  D) Ag
  Show Answer
  The correct answer is B .
• Question 856: Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises? Options:
  A) The bonds in the reacting molecules are more readily broken
  B) The molecular collisions become more violent
  C) A lower proportion of the molecules has the necessary minimum energy to react
  D) The collision frequency of the molecules increase
  Show Answer
  The correct answer is D .
• Question 857: The simplest branched-chain hydrocarbon is Options:
  A) ethane
  B) ethene
  C) propane
  D) butane
  Show Answer
  The correct answer is D .
• Question 858: In the chemical reaction A + B $\to$ C + D, more of D is formed? Options:
  A) if the concentrated of A is reduced
  B) if the concentrated of B is reduced
  C) if the concentrated of C is reduced
  D) if the concentration of C is increased
  E) if D is continuously removed from the reaction mixture
  Show Answer
  The correct answer is E .
• Question 859: Starch can be converted to ethyl alcohol by Options:
  A) distillation
  B) fermentation
  C) isomerization
  D) cracking
  E) cooking
  Show Answer
  The correct answer is B .
• Question 860: The carbon atoms on ethane are Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp⁴ hybridized
  D) sp hybridized
  Show Answer
  The correct answer is B .