WAEC Chemistry questions

357 questions with answers and explanations. Tap an option to check yourself.

All topics Acids, bases and salts · 26 Air · 16 Atomic structure and bonding · 26 Chemical combination · 27 Chemical equilibrium · 16 Chemistry and industry · 17 Electrolysis · 19 Energy changes · 16 Environmental pollution · 15 Kinetic theory of matter and gas laws · 18 Metals and their compounds · 23 Non-metals and their compounds · 22 Organic compounds · 29 Oxidation and reduction · 19 Rates of chemical reaction · 16 Separation of mixtures and purification · 18 Solubility · 16 Water · 18

Question 341· Water· WAEC
Water from a well tastes better than distilled water because it contains
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Answer: B. dissolved gases and minerals
Explanation and discussion
Question 342· Water· WAEC
Which substance is added during public water treatment to kill germs?
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Answer: B. chlorine
Explanation and discussion
Question 343· Water· WAEC
Hard water is undesirable for washing because it
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Answer: C. wastes soap by forming scum
Explanation and discussion
Question 344· Water· WAEC
The formula of water shows that it contains hydrogen and oxygen in the ratio, by atoms, of
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Answer: A. 2 : 1
Explanation and discussion
Question 345· Water· WAEC
A test for pure water is that it
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Answer: B. boils at 100 °C at standard pressure
Explanation and discussion
Question 346· Water· WAEC
Anhydrous copper(II) sulphate is used to test for water because it turns from
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Answer: D. white to blue
Explanation and discussion
Question 347· Water· WAEC
In water treatment, alum is added to
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Answer: D. coagulate fine suspended particles
Explanation and discussion
Question 348· Water· WAEC
Temporary hardness in water is caused by dissolved
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Answer: A. calcium hydrogentrioxocarbonate(IV)
Explanation and discussion
Question 349· Water· WAEC
Boiling removes temporary hardness because calcium hydrogencarbonate
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Answer: C. decomposes to insoluble calcium carbonate
Explanation and discussion
Question 350· Water· WAEC
Temporary hardness of water can be removed by
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Answer: C. boiling
Explanation and discussion
Question 351· Water· WAEC
In water treatment, the water is passed through sand beds in order to
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Answer: D. filter out suspended particles
Explanation and discussion
Question 352· Water· WAEC
The test for water is that it turns anhydrous copper(II) sulphate
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Answer: D. from white to blue
Explanation and discussion
Question 353· Water· WAEC
Rain water is the purest natural water, but it may contain dissolved
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Answer: C. gases from the air
Explanation and discussion
Question 354· Water· WAEC
Which of the following methods removes temporary hardness of water but not permanent hardness?
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Answer: B. Boiling
Explanation and discussion
Question 355· Water· WAEC
Permanent hardness can be removed by adding
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Answer: D. washing soda (sodium carbonate)
Explanation and discussion
Question 356· Water· WAEC
Caustic soda pellets left open in the laboratory become wet and finally form a solution. They are
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Answer: D. deliquescent
Explanation and discussion
Question 357· Water· WAEC
White anhydrous copper(II) tetraoxosulphate(VI) turns blue when it
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Answer: C. absorbs water
Explanation and discussion

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WAEC Chemistry questions

Water from a well tastes better than distilled water because it contains

Which substance is added during public water treatment to kill germs?

Hard water is undesirable for washing because it

The formula of water shows that it contains hydrogen and oxygen in the ratio, by atoms, of

A test for pure water is that it

Anhydrous copper(II) sulphate is used to test for water because it turns from

In water treatment, alum is added to

Temporary hardness in water is caused by dissolved

Boiling removes temporary hardness because calcium hydrogencarbonate

Temporary hardness of water can be removed by

In water treatment, the water is passed through sand beds in order to

The test for water is that it turns anhydrous copper(II) sulphate

Rain water is the purest natural water, but it may contain dissolved

Which of the following methods removes temporary hardness of water but not permanent hardness?

Permanent hardness can be removed by adding

Caustic soda pellets left open in the laboratory become wet and finally form a solution. They are

White anhydrous copper(II) tetraoxosulphate(VI) turns blue when it