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 91: Which of the following statements about phosphorus is NOT correct? Options:
  A) Phosphorus is a solid mineral
  B) Phosphorus is obtained by oxidation reaction of phosphate
  C) Phosphorus exists in two allotropic forms
  D) Both forms of phosphorus are interconvertible
  E) Yellow phosporus ignites when rubbed on a rough surface
  Show Answer
  The correct answer is E .
• Question 92: Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals? Options:
  A) 13.0
  B) 7.0
  C) 6.5
  D) 3.0
  Show Answer
  The correct answer is D .
• Question 93: Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas? Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is B .
• Question 94: A mixture of 0.20 mole of Ar, 0.20 mole of N₂ and 0.30 mole of He exerts a total pressure of 2.1 atm. The partial pressure of He in the mixture is? Options:
  A) 0.90 atm
  B) 0.80 atm
  C) 0.70 atm
  D) 0.60 atm
  Show Answer
  The correct answer is A .
• Question 95: Carbohydrates are large molecules with the molecular formula C _x (H₂O)_y. In which of the following pairs is x not equal to y? Options:
  A) glucose and starch
  B) maltose and starch
  C) sucrose and fructose
  D) maltose and starch
  Show Answer
  The correct answer is A .
• Question 96:

  Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below?

  2HCl + CaCO${}_3$ → CaCl${}_2$ + H${}_2$O + CO${}_2$

  Options:
  A) Increasing the concentration of the acid
  B) Increasing the surface area of CaCO${}_3$
  C) A and B
  D) Reducing the concentration of the acid
  Show Answer
  The correct answer is C .
• Question 97:

  Which noble gas is radioactive and is produced as a decay product of uranium and thorium?

  Options:
  A) Argon
  B) Krypton
  C) Radon
  D) Neon
  Show Answer
  The correct answer is C .
• Question 98:

  What is the state of matter in which particles are widely spaced and move freely with high kinetic energy?

  Options:
  A) Liquid
  B) Solid
  C) Plasma
  D) Gas
  Show Answer
  The correct answer is D .
• Question 99:

  A sample of any of the following substances disappearsafter some time when exposed to air like camphor, naphthalene, or dry ice. This phenomenon is called?

  Options:
  A) Sublimation
  B) Evaporation
  C) Diffusion
  D) Radiation
  Show Answer
  The correct answer is A .
• Question 100:

  Sodium reacts vigorously with water to produce

  Options:
  A) Sodium chloride (NaCl) and oxygen gas (O2)
  B) Sodium nitrate (NaNO3) and water (H2O)
  C) Sodium hydroxide (NaOH) and hydrogen gas (H2)
  D) Sodium oxide (Na2O) and hydrogen gas (H2)
  Show Answer
  The correct answer is C .