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1991 - WAEC Chemistry Past Questions and Answers - page 3

21

In the redox reaction represented by the following equation: Cu2+

A
the oxidation number of copper increases
B
copper (ll) ions are reduced to copper atoms
C
zinc atoms are reduced to zinc ions
D
copper (ll) ions donate electrons to zinc atoms
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22

When starch undergoes complete enzyme-catalyzed hydrolysis, the resulting product is

A
glucose
B
maltose
C
sucrose
D
fructose
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23

Which of the reactions represented by the following equations will take place at room temperature?

A
C 6 H2O → CO + H2
B
CuO + H2 → Cu + H2O
C
N2 + 3H2 → 2NH3
D
2Na + 2H2O → 2NaOH + H2
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24

Which of the following is not a direct petroleum product?

A
Methane
B
Ethanol
C
Petrol
D
Vaseline
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25

How many principal electronic shells has an atom whose electronic configuration is shown below? 1s22s22p63s1

A
1
B
2
C
3
D
4
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26

Which of the following properties is not characteristic of electrovalent compounds?

A
formation of crystalline solids
B
solubility in polar solvents
C
high vapour pressures
D
high melting and boiling points
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27

Compounds that have the same molecular formula but different structures are said to be

A
allotropic
B
polymorphic
C
polymeric
D
isomeric
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28

In which of the following crystals are the particles held by van der Waal's forces only?

A
Sodium chloride
B
Ice
C
Diamond
D
Iodine
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29

A current of 4.0 amperes was passed through copper (ll) tetraoxosulphate (IV) solution for one hour using copper electrodes. What was the mass of copper deposited? (Cu = 64, 1F = 96500 C)

A
3.2g
B
4.8g
C
6.4g
D
48g
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30

When a crystal was added to its solution, it did not dissolve and the solution remained unchanged, showing that the solution was

A
concentrated
B
supersaturated
C
unsaturated
D
colloidal
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