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1991 - WAEC Chemistry Past Questions and Answers - page 1

1

The metal extracted from cassiterite is

A
calcium
B
copper
C
tin
D
sodium
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2

In which of the following is the oxidation number of nitrogen zero?

A
SO2 and NH3
B
NaNO3
C
HNO2
D
NOI3
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3

The separation of a mixture of calcium trioxocarbonate (lV) and sodium trioxocarbonate (IV) is most easily carried out by using the differences in their

A
physical states
B
melting points
C
Rf. values
D
solubility
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4

When air is passed through a heated tube containing finely divided copper, the component that is absorbed in the process is

A
carbon (IV) oxide
B
nitrogen
C
oxygen
D
water vapour
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5

What is the amount (in mole) of sodium trioxocarbonate (IV) in 5.3 g of the compound? (Na2CO3 = 106)

A
0.05
B
0.10
C
0.20
D
0.50
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6

Which of the processes represented by the following equations has the greatest positive entropy change?

A
C6H3(l) → C6H 6 (g)
B
H2O (s) → H2O(l)
C
CuO(s) + H2(g) → Cu(s) + H2
D
Na2CO3(s) + nH2O(l) →Na 2CO3nH2O(s)
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7

Which of the following elements can from more than one acidic oxide?

A
Hydrogen
B
Sulphur
C
Carbon
D
Alumium
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8

CH2 = CH2 + H2SO4 → CH3 - CH2 -OSO3H. The reaction illustrated by the equation above is an example of

A
substitution
B
oxidation
C
reduction
D
addition
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9

Brass is an alloy of copper and

A
iron
B
chromium
C
zinc
D
tin
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10

Which of the following formula is that of a dicarboxylic acid?

A
(CH3CH 2)2CHCOOH
B
CH2(OH)2
C
CH3CH(OH)COOH
D
CH2(COOH)2
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