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 291:
  

  Use the section of the periodic table above to answer this question.

  Which of the indicate an alkali metal and a noble gas respectively?

  Options:
  A) M and E
  B) G and E
  C) R and L
  D) G and L
  Show Answer
  The correct answer is D .
• Question 292:

  ²²⁶₈₈Ra → ^x₈₆Rn + α - particle

  What is the value of x in the nuclear reaction above?

  Options:
  A) 220
  B) 222
  C) 226
  D) 227
  Show Answer
  The correct answer is B .
• Question 293: Ethyne is passed through a hot tube containing organo-nickel catalyst to produce Options:
  A) isoprene
  B) polythene
  C) ethanol
  D) benzene
  Show Answer
  The correct answer is D .
• Question 294:

  At 25^o and zymase as catalyst,

  C₆H₁₂₆ → 2C₂H₅OH + 2CO₂ + energy

  The reaction above represented by the equation above is useful in the production of

  Options:
  A) propanol
  B) butanol
  C) methanol
  D) ethanol
  Show Answer
  The correct answer is D .
• Question 295: Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? Options:
  A) Z is efflorescent
  B) Y and Z are efflorescent
  C) Y and Z are deliquescent
  D) Y and Z are hygroscopic
  E) Y is deliquescent
  Show Answer
  The correct answer is C .
• Question 296: When H₂S gas is passed into a solution of iron (III) chloride, the colour changes from yellow to green. This is because? Options:
  A) H_(s)S is reduced to S
  B) Fe³⁺ ions are oxidized by H_(s)S
  C) Fe³⁺ ions are oxidized Fe³⁺ ions
  D) Fe³⁺ ions are reduced to Fe²⁺ ions
  Show Answer
  The correct answer is D .
• Question 297:

  A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as

  Options:
  A) A reversible reaction
  B) A spontenous reaction
  C) An endothermic reaction
  D) An exothermic reaction
  Show Answer
  The correct answer is D .
• Question 298:

  At 27°C, 58.5g of sodium chloride is present in 250cm${}^3$ of a solution. The solubility of sodium chloride at this temperature is?

  (molar mass of sodium chloride = 111.0gmol${}^{-1}$)

  Options:
  A) 2.0 moldm${}^{-3}$
  B) 0.25 moldm${}^{-3}$
  C) 1.0 moldm${}^{-3}$
  D) 0.5 moldm${}^{-3}$
  Show Answer
  The correct answer is A .
• Question 299: Which of the followingstatements is TRUE? Options:
  A) The dissolution of NaOH_(s) in water is endothermic
  B) The heat os solution of NaOH_(s) is positive
  C) The NaOH_(s) gains heat from the surroundings
  D) The heat of solution of NaOH_(s) is negative
  Show Answer
  The correct answer is D .
• Question 300: In which of the following is the entropy change positive? Options:
  A) Thermal dissociation of ammonium chloride
  B) Reaction between an acid and a base
  C) Addition of concentrated acid to water
  D) Dissolution of sodium metal in water
  Show Answer
  The correct answer is A .