Chemistry 2018 Past Questions | WAEC

Study the following Chemistry past questions and answers for JAMBWAEC  NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.

31. When chlorine is passed through a sample of water, the pH of the water sample would be

  • A. < 7
  • B. > 7
  • C. = 7
  • D. 0

32.  How many atoms are contained in 0.2moles of nitrogen? \([N_{A} = 6.02 \times 10^{23}]\)

  • A. \(1.20 \times 10^{23}\)
  • B. \(2.41 \times 10^{23}\)
  • C. \(3.62 \times 10^{23}\)
  • D. \(4.82 \times 10^{23}\)

33. The strength of metallic bonds depends on the 

  • A. charge density of the atoms
  • B. ductility of the metal
  • C. number of valence electrons
  • D. total number of electrons in the atom

34.  When zinc is added to AgNO\(_{3}\) solution, crystals of silver forms on the zinc surface. This indicates that zinc is

  • A. oxidised
  • B. reduced
  • C. decomposed
  • D. dissociated

35.  The empirical formula of a compound containing 0.067mol Cu and 0.066mol O is    [Cu = 63.5, O = 16]

  • A. \(Cu_{2}O\)
  • B. \(CuO\)
  • C. \(CuO_{2}\)
  • D. \(CuO_{4}\)

36.  The change in the oxidation state of iron in the reaction represented by the equation:  \(2FeCl_{3} + H_{2}S \to 2FeCl_{2} + 2HCl + S\)  is

  • A. +2 to +3
  • B. 0 to +2
  • C. +3 to +2
  • D. +3 to 0

37. Which of the following methods can be used to seperate blood cells from plasma?

  • A. Centrifugation
  • B. Filtration
  • C. Chromatography
  • D. Distillation

38. Which of the following statements is true about ionic radius? Ionic radius

  • A. increases as nuclear charge increases
  • B. decreases as nuclear charge increases
  • C. decreases as nuclear charge decreases
  • D. remains constant as nuclear charge increases

39. Analysis of a hydrocarbon shows that it contains 0.93g of Carbon per gram of the compound. The mole ratio of carbon to hydrogen in the compound is [H = 1.0, C=12.0]

  • A. 1:1
  • B. 1:2
  • C. 2:1
  • D. 2:3

40. The law of definite proportions states that

  • A. pure samples of the same compound contain the same elements combined in the same proportion by mass
  • B. pure samples of substances are in the same proportion by mass
  • C. chemical compounds are pure because they contain the same elements
  • D. matter can neither be created nor destroyed.

Post suggestions Here

Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments
0 0 votes
Article Rating
0
Would love your thoughts, please comment.x
()
x
Scroll to Top