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 2141:

  The scientist who stated that matter can be converted into energy is?

  Options:
  A) Boyle
  B) Lavoiser
  C) Avogadro
  D) Einstein
  Show Answer
  The correct answer is D .
• Question 2142:

  Sodium sulphate decahydrate (Na₂SO₄.10 H₂O) on exposure to air loses all its water of crystallization.

  The process of loss is known as

  Options:
  A) efflorescence
  B) hygroscopy
  C) deliquescence
  D) effervescence
  E) dehydration
  Show Answer
  The correct answer is A .
• Question 2143: For iodine crystals to sublime on heating, the molecules must acquire energy that is? Options:
  A) less than the forces odf attraction in the solid
  B) equal to the forces of attraction in th solid
  C) necessary to melt the solid
  D) greater than the forces of attraction in both the solid and the liquid phases
  Show Answer
  The correct answer is D .
• Question 2144:

  Which of the following is a common property of non-metals?

  Options:
  A) Exist as solids at room temperature
  B) Tend to gain electrons in chemical reactions
  C) High thermal conductivity
  D) Readily form cations in chemical reactions
  Show Answer
  The correct answer is B .
• Question 2145: In the reaction of oxygen with hydrogen to produce water, which of the following statements is true? Options:
  A) One atom of hydrogen reacts with two atoms of oxygen to give one molecule of water
  B) Two atoms of hydrogen react with two atoms of oxygen to give two molecules of water
  C) One molecule of oxygen reacts with one molecule of hydrogen to give two molecules of water
  D) One molecule of hydrogen reaccts with two molecules of oxygen to give three molecules of water
  E) One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
  Show Answer
  The correct answer is E .
• Question 2146: The knowledge of half-life can be used to Options:
  A) create an element
  B) detect an element
  C) spilt an element
  D) irradiate an element
  Show Answer
  The correct answer is B .
• Question 2147: In countries where the temperature fall below 273k, salt always spilled on the ray road in order to Options:
  A) increase the making point office
  B) increase the density of the ice
  C) make the ice impure
  D) rinse the making point of the ice
  Show Answer
  The correct answer is A .
• Question 2148: If 30cm³ of oxygen diffuses through porous plug in 7s, how long will it take 60 cm³ of chlorine to diffuse through the same plug? Options:
  A) 12s
  B) 14s
  C) 21s
  D) 30s
  Show Answer
  The correct answer is C .
• Question 2149: A side effect of soft water is that Options:
  A) it gives offensive taste
  B) excess calcium is precipitated
  C) it attacks lead contained in pipes
  D) it encourage the growth of bacteria
  Show Answer
  The correct answer is C .
• Question 2150:

  

  The diagram above represents an atom that can combine with chlorine to form

  Options:
  A) a covalent bond
  B) an electrovalent bond
  C) a hydrogen bond
  D) a co-ordinate bond
  Show Answer
  The correct answer is B .