Waec Chemistry 2021 Past Questions and Answers

Question 31:

• WAEC 2021

The 25°C evaporation of a 100 cm\(^{3}\) solution of K\(_{2}\)CO\(_{3}\) to dryness gave 14g of the salt. What is the solubility of K\(_{2}\)CO\(_{3}\) at 25°25C? [K\(_{2}\)CO\(_{3}\) = 138]

A. 0.01 mol dm\(^{-3}\)
B. 0.101 mol dm\(^{-3}\)
C. 1.01 mol dm \(^{-3}\)
D. 10.0 mol dm\(^{-3}\)

Question 32:

• WAEC 2021

How many molecules of oxygen would occupy a volume of 2.24 cm\(^{3}\) at s.t.p?
[Molar volume at s.t.p = 22,400 cm\(^{3}\), Avogadro's number = 6.02 x 10\(^{23}\)]

A. 3.01 x 10\(^{20}\)
B. 3.01 x 10\(^{27}\)
C. 6.02 x 10\(^{19}\)
D. 6.02 x 10\(^{27}\)

Question 33:

• WAEC 2021

The isotopes of neon are represented by the symbols \(^{20}\)\(_{x}\) Ne, \(^{21}\) \(_{y}\) Ne, and \(^{22}\) \(_{z}\) Ne. The relationship between x, y, and z is?

A. X > y > z
B. X < y < z
C. X = y= z
D. X < z < y

Question 34:

• WAEC 2021

Which of the following pairs of molecules form hydrogen bonds?

A. C\(_{2}\)H\(_{5}\)OH and CH\(_{3}\)OH
B. CH\(_{3}\)OH and H\(_{2}\)
C. H\(_{2}\)S and CH\(_{4}\)
D. NH\(_{3}\) and SO\(_{2}\)

Question 35:

• WAEC 2021

Which of the following statements about elements in Group VII is correct?

A. Br\(_{2}\) will oxidize CI\(^{-}\)
B. F\(_{2}\) has the least tendency to be reduced
C. Cl\(_{2}\) will oxidize I\(^{-}\)
D. L\(_{2}\) is a stronger oxidizing agent than F\(_{2}\)