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 1561: When sodium nitrate dissolves in water, ∆H is positive. This means that? Options:
  A) the reaction is catalysed
  B) the reaction is complete
  C) the reaction is exothermic
  D) the reaction is endthermic
  E) sodium nitrate is highly soluble in water
  Show Answer
  The correct answer is D .
• Question 1562:

  CO_(g) + H₂ O_(g) → CO_2(g) + H_2(g)

  Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) and CO_(g) in KJ mol ^-1 are - 394 -242 and - 110 respectively.

  Options:
  A) + 262 KJ mol ^-1
  B) - 262 KJ mol ^-1
  C) + 42 KJ mol ^-1
  D) - 42 KJ mol ^-1
  Show Answer
  The correct answer is D .
• Question 1563:

  Which of the following gases contains the least number of atoms at s.t.p?

  Options:
  A) 1 mole of butane
  B) 4 moles of chlorine
  C) 3 moles of ozone
  D) 7 moles of argon
  Show Answer
  The correct answer is A .
• Question 1564:

  Na₂S₂O_3(aq) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l)

  Which of the following would introduce the greatest increase in the rate of the chemical reaction above?

  Options:
  A) An increase in temperature and decrease in the concentration of the reactant
  B) A decrease in the volume and increase in the pressure of the reactant
  C) A decrease in the temperature and an incease in the concentration of the reactant
  D) An increase in temperature and an increase in the concentration of the reactant
  Show Answer
  The correct answer is D .
• Question 1565: The enzymes responsible for converting sucrose into two simple isomeric sugars is Options:
  A) maltase
  B) amylase
  C) invertase
  D) lactase
  Show Answer
  The correct answer is C .
• Question 1566: Elements in the same period in the periodic table have the same Options:
  A) number of shells
  B) atomic number
  C) chemical properties
  D) physical properties
  Show Answer
  The correct answer is A .
• Question 1567: A molar solution of caustic soda is prepared by dissolving Options:
  A) 40 g NaOH in 100 g of water
  B) 40 g NaOH in 1000 g of water
  C) 20 g NaOH in 500 of solution
  D) 20 g NaOH in 1000 g of solution
  E) 2o g NaOH in 80 g of solution
  Show Answer
  The correct answer is B .
• Question 1568: Which of the following is a neutralization reaction? Options:
  A) Addition of sodium chloride solution to potassium chloride solution
  B) Addition of trioxonitrate (V) acid (nitric acid) to distilled water
  C) Addition of trioxonitrate (V) acid (nitric acid) to tetraoxosulphate (IV) acid (sulphuric acid)
  D) Addition of trioxonitrate (V) acid (nitric acid) to potassium trioxonitrate (V) (potassium nitrate) solution
  E) Addition of trioxonitrate (V) acid (nitric acid) to potassium hydroxide solution
  Show Answer
  The correct answer is E .
• Question 1569:

  What is the common name for ethanoic acid?

  Options:
  A) Acetic acid
  B) Butyric acid
  C) Propionic acid
  D) Formic acid
  Show Answer
  The correct answer is A .
• Question 1570: The reaction between an organic acid and an alcohol in the presence of an acid catalyst is known as; Options:
  A) saponification
  B) dehydration
  C) esterification
  D) hydrolysis
  E) hydration
  Show Answer
  The correct answer is C .