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 401:

  The ions X_- and Y₊ are isoelectronic, each containing a total of 10 electrons.

  How many protons are in the nuclei of the neutral atoms of X and Y respectively?

  Options:
  A) 10 and 10
  B) 9 and 9
  C) 11 and 9
  D) 9 and 11
  Show Answer
  The correct answer is D .
• Question 402:

  2SO_2(g) + O_2(g) ↔ 2SO_3(g)

  ΔH = -189 kJ mol^-1

  The equilibrium constant for the reaction above is increased by

  Options:
  A) Increasing the temperature of the system
  B) Increase the pressure of the system
  C) The addition of a catalyst to the system
  D) Increasing the surface area of the vessel
  Show Answer
  The correct answer is B .
• Question 403: Which of the following is a physical change? Options:
  A) The bubbling of chlorine into water
  B) The bubbling of chlorine into a jar contanining hydrogen
  C) The dissolution of sodium chloride in water
  D) The passing of steam over heated iron
  Show Answer
  The correct answer is C .
• Question 404: Phosphorus burns in oxygen according to the equation P₄ + 50₂ → P₄O₁₀. How many litres of oxygen will be required at S.T.P for complete oxidation of 12.4g of phosphorus? [P = 31,O = 16 and molar volume of a gas at S.T.P = 22.4 litres] Options:
  A) 5. 20
  B) 11. 20
  C) 2. 24
  D) 20. 20
  E) 6. 20
  Show Answer
  The correct answer is B .
• Question 405:

  .....................P....Q.....R......S

  Proton..............13....16....17.....19

  Electron............13....16....17.....19

  Neutron.............14....16....35.....20Which of the four atoms P,q,R and in S in the above data can be described by the following properties relative atomic mass is greater than 30 but less than 40; it has an odd atomic number and forms a unipositive ion in solution?

  Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is D .
• Question 406:

  

  Which of the structural forms above is ethanoic acid is

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is E .
• Question 407:

  The shape of ammonia molecule is?

  Options:
  A) Trigonal planar
  B) Octahedral
  C) Square planar
  D) Tetrahedral
  Show Answer
  The correct answer is A .
• Question 408: Which of the following substances would you see as an indicator in the titration of sodium carbonate solution against hydrochloric acid (complete neutralisation)? Options:
  A) Litmus paper
  B) Phenolphthalein
  C) Methyl orange
  D) Universal indicator
  E) None of these
  Show Answer
  The correct answer is C .
• Question 409:

  

  The IUPAC nomenclature for the compound above is

  Options:
  A) 4-methylpent-1-ene
  B) 3-methylpent-2-ene
  C) 2-methylpent-1ene
  D) 2-methylpent-4-ene
  Show Answer
  The correct answer is A .
• Question 410:

  Which functional group is present in alkanals?

  Options:
  A) Carbonyl group (C=O)
  B) Hydroxyl group (-OH)
  C) Alkyl group (-R)
  D) Carboxyl group (-COOH)
  Show Answer
  The correct answer is A .