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 281: The salt that will form a precipitate soluble in excess ammonia solution is Options:
  A) Ca(NO₃)₂
  B) Cu(NO₃₎₂
  C) Mg(NO₃₎₂
  D) Al(NO₃₎₃
  Show Answer
  The correct answer is B .
• Question 282:

  On which of the following is the solubility of a gaseous substance dependent? 

  I. Nature of solvent 

  II. Nature of solute 

  III. Temperature 

  IV. Pressure

  Options:
  A) I, II, III and IV
  B) I and II only
  C) II only
  D) I, III and IV only
  Show Answer
  The correct answer is D .
• Question 283: A compound contains 40.0% C, 6.7% H 53.3% O. If the molecular mass of the compound is 180, its molecular formula is [C =12, H =1,O] Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₆O₃
  D) C₆H₁₂O₆
  Show Answer
  The correct answer is D .
• Question 284: In a neutralization reaction involving HCI and NaOH using litmus as indicator, the colour at the end point is Options:
  A) Blue
  B) Red
  C) Orange
  D) Purple
  Show Answer
  The correct answer is C .
• Question 285:

  What is the trend for ionization energy across a period in the periodic table?

  Options:
  A) Increases from left to right.
  B) Remains constant
  C) Varies randomly
  D) Decreases from left to right
  Show Answer
  The correct answer is A .
• Question 286:

  What weight of NaCl is needed to make 2.0 dm³ of a 1.5M solution?

  [Na = 23, Cl = 35.5]

  Options:
  A) 116 g
  B) 175 g
  C) 87 g
  D) 58 g
  Show Answer
  The correct answer is B .
• Question 287:

  The electronic configuration of element Z is 1s${}^2$ 2s${}^2$ 2p${}^6$ 3s${}^2$ 3p${}^1$. What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion.

  Options:
  A) Z${}_3$(SO${}_4$)${}_2$
  B) ZSO${}_4$
  C) Z${}_2$ SO${}_4$
  D) Z${}_2$(SO${}_4$)${}_3$
  Show Answer
  The correct answer is D .
• Question 288:

  Sulphur exists in six forms in the solid state. This property is known as

  Options:
  A) Isomerism
  B) Allotropy
  C) Isotopy
  D) Isomorphism
  Show Answer
  The correct answer is B .
• Question 289:

  

  In the diagram above, Y is a mixture of

  Options:
  A) calcium hydroxide and ammonium chloride
  B) calcuim hydroxide and sodium chloride
  C) sodium chloride and ammonuim trioxonitrate (V)
  D) sodium dioxonitrate (lll) and ammouium chloride
  Show Answer
  The correct answer is A .
• Question 290: The filter in the cigarette reduces the nicotine content by Options:
  A) Burning
  B) Adsorption
  C) Evaporation
  D) Absorption
  Show Answer
  The correct answer is B .