Waec 2022 Chemistry Past Questions And Answers
If 50 cm3 of a saturated solution of KNO3 at 40oC contained 5:05 g of the salt, its solubility at the same temperature would be [KNO3 = 101]
- A. 1.0 mol dm?3
- B. 1.5 mol dm?3
- C. 2.0 mol dm?3
- D. 5.0 mol dm?3
Which of the following statements about atoms of a metal is correct? They
- A. readily accept electrons
- B. are soft
- C. are held together by covalent bond
- D. are held together by a sea of electron cloud
Which of the following elements would displace copper from a solution of copper ions?
- A. silver
- B. gold
- C. lead
- D. mercury
Ionization energy increases across the period in the periodic table because
- A. atomic number increases
- B. effective nuclear charge increases
- C. mass number decreases
- D. screening effect decreases
What amount of electricity is required to deposit one mole of aluminium from a solution of AlCl3?
- A. One Faraday
- B. One ampere
- C. Three Faradays
- D. Three amperes
What is the percentage composition of carbon in Ca(HCO3)2 ? [ Ca = 40.0, 0= 16.0, C = 12.0, H= 1.0]
- A. 22.2%
- B. 14.8%
- C. 7.4%
- D. 3.7%
The by-product of fermentation of sugar is
- A. carbon(IV) oxide.
- B. ethanoic acid.
- C. propanol
- D. propan-1, 2, 3- triol.
The maximum number of covalent bonds formed by nitrogen is
- A. 1
- B. 2
- C. 3
- D. 4
Consider the following reaction equation N2(g) + 3H2(g); ?H = -92kJ
- A. shift the equilibrium to the right
- B. increase the yield of ammonia
- C. decrease the amount of hydrogen
- D. decrease the yield of ammonia
(a) Describe the observation that would be made when-----
i. Sulphur is heated from room temperature till 1190C
ii. 50% trioxonitrate(V) acid acts on copper tunings
(b)i. State two gaseous pollutants that can be generated by burning coal.
ii. What gas is responsible for most of the explosions in coal mines?
iii. The mining of coal leads to environmental pollution. State two environmental effects of the mining activity.
iv. Explain briefly why coal burns more easily when it is in pieces than in lump form
v. Name the non-volitile residue after the destructive distillation of coal
(c)i. Describe a chemical test for water
ii.a. State the effect of boiling a temporary hard water
b. State the effect of adding sodium trioxocarbonate(IV) crystals to permanent hard water
iii. Write an equation for the process of boiling a temporary hard water
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