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 1351: The constituents of baking powder that makes the dough to rise is Options:
  A) NaHCO₃
  B) NaOH
  C) Na₂CO₃
  D) NaCl
  Show Answer
  The correct answer is A .
• Question 1352:

  Temp (°C)	25	35	45
  Time (seconds)	72	36	18

  The times taken for iodine to be liberated in the reaction between sodium thiosulphate and hydrochloric acid at various temperature are as follows. These results suggest that

  Options:
  A) for a 10^o rise in temperature, rate of reaction is double
  B) for a 10 ^o rise in temperature, rate of reaction is halved
  C) time taken for iodine to appear does not depend on temperature
  D) for a 10 ^o rise in temperature rate of reaction is tripled
  Show Answer
  The correct answer is A .
• Question 1353:

  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 1354: One method of driving the position of equilibrium of an endothermic reaction forward is to? Options:
  A) increase temperature at constant pressure
  B) dcrease pressure at constant temperature
  C) cool down the apparatus with water
  D) decreases temperature at constant pressure
  Show Answer
  The correct answer is A .
• Question 1355:

  

  The diagram above best illustrates the effect of decrease in

  Options:
  A) concentration
  B) temperature
  C) surface area
  D) pressure
  Show Answer
  The correct answer is A .
• Question 1356:

  Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

  Options:
  A) Fractional distillation
  B) Filtration followed by distillation
  C) Neutralization with sodium hydroxide followed by distillation
  D) Neutralization with sodium hydroxide followed by filtration
  Show Answer
  The correct answer is B .
• Question 1357:

  What is the PH of 0.00 1 moldm${}^3$ solution of the sodium hydroxide

  Options:
  A) 14
  B) 13
  C) 12
  D) 11
  Show Answer
  The correct answer is D .
• Question 1358: Which of the following metals does NOT form a stable trioxocarbonate (IV)? Options:
  A) Fe
  B) Al
  C) Zn
  D) Pb
  E) none of the options is correct
  Show Answer
  The correct answer is E .
• Question 1359: Which are the correct IUPAC names for H-CO₂CH₃ and CH = CH Options:
  A) Methyl methanoate and ethene
  B) Metanoic acid and ethyne
  C) Ethyl methanoate and ethyne
  D) Methyl methanoate and ethyne
  E) Ethanoic acid and ethene
  Show Answer
  The correct answer is A .
• Question 1360: The flame used by welders in cutting metals is Options:
  A) butane gas flame
  B) acetylene flame
  C) kerosene flame
  D) oxy-acetylene flame
  E) oxygen flame
  Show Answer
  The correct answer is D .