Waec Chemistry 2020 Past Questions and Answers

Question 31:

• WAEC 2020

What volume of oxygen at s.t.p is required to burn completely 7.5 dm${}^3$ of methane according to the following equation?
CH${}_4$ ${}_g$ + 20${}_2$ ${}_g$ → CO${}_2$ ${}_g$ + H${}_2$O${}_g$

A. 3.75 dm${}^3$
B. 7.59 dm${}^3$
C. 15.0 dm${}^3$
D. 30.0dm${}^3$

Question 32:

• WAEC 2020

When 250 cm3 of a saturated solution of CuSO${}_4$ at 30°C was evaporated to dryness, 5.0 g of the salt was obtained..
What is the solubility of the salt at 30°C? [CuSO${}_4$ = 160]

A. 0.031
B. 0.125
C. 0.640
D. 1.560

Question 33:

• WAEC 2020

The bond between NH${}_3$ and H${}^{+}$ in NH4${}^{+}$ is?

A. Dative
B. Covalent
C. Hydrogen
D. Electrovalent

Question 34:

• WAEC 2020

Which of the following oxides has a giant covalent structure?

A. Al${}_2$O${}_3$
B. Na${}_2$O
C. P${}_4$O${}_{1}0$
D. SiO${}_2$

Question 35:

• WAEC 2020

Which of the following hydroxides is not readily soluble in water?

A. NH${}_4$OH
B. Ca(OH)${}_2$
C. NaOH
D. KOH