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WAEC - Chemistry (1994)

1
The components of universal indicator solution can best be separated by
Answer
(A)
chromatography
2
The number of replaceable hydrogen atoms in one acid indicates its
Answer
(A)
basicity
3
Catalytic hydrogenation of alkenes produces compounds with the general formula
Answer
(C)
CnH2n+2
4
A measure of the degree of disorder in a chemical system is known as the
Answer
(D)
entrophy
5
In any chemical reaction, the total mass of the products is always equal to that of the reactants. This is statement of the law of
Answer
(B)
conservation of matter
6
Which of the following is not a property of magnesium oxide?
Answer
(E)
Low binding energy
7
Which of the following would increase the rate of reaction of chips of a metal M as shown in the equation below? M(s) + 2HCI(aq) → MCI2(aq) + H2(g)
Answer
(D)
Grinding the metal into powder
8
The oxidation number of phosphorus in \(PO_4^{3-}\) is
Answer
(E)
+5
9
The number of atoms in 1.2g of carbon - 12 isotope is
Answer
(B)
6.02 x 1022
10
Tetraoxosulphate (lV) acid is described as strong acid because it is highly
Answer
(E)
ionized in water
11
The following will decolourize acidified potassium tetraoxomanganate (VII) solution except
Answer
(C)
pentane
12
Polyatomicity is illustrated by molecules of
Answer
(A)
sulphur
13
Calcium is usually extracted by the electrolysis of its
Answer
(E)
chloride
14
When naphthalene on heating changes from the solid state directly to the gaseous state it undergoes
Answer
(B)
sublimation
15
Which of the following occurs when an aqueous solution of sodium hydroxide is electrolysed using graphite electrodes?
Answer
(C)
Oxygen gas is produced at the anode
16
If the volume of a given mass of gas at 0oC is 27.3cm3, what will be the volume of the gas at 10oC, pressure remaining constant?
Answer
(B)
28.3cm3
17
Glucose can be obtained from starch by
Answer
(C)
hydrolysis
18
How many faradays of electricity are required to liberate 9g aluminium? (AI = 27)
Answer
(C)
1.0
19
When water is dropped on calcium carbide, the gaseous product is an
Answer
(C)
alkyne
20

Mg\(_2\) + 2HCI\(_{(aq)}\) → MgCI\(_{2(g)}\) + H\(_{2(g)}\).

From the equation above what mass of hydrogen would be produced if 12.0 g of magnesium reacted completely with dilute hydrochloric acid? (H = 1, Mg = 24)

Answer
(A)
1.0g
21
The positive of an element in the Periodic Table is determined by
Answer
(D)
the number of protons in its atom
22
Which of the following electronic structures belongs to a noble gas?
Answer
(C)
1s22s22p63s23p6
23
In a chemical reaction, the reacting species possess energy of motion known as
Answer
(D)
kinetic energy
24
The following compounds will decompose on heating except
Answer
(B)
K2CO3
25
Which of the following reactions is accompanied by the first ionization energy of an element X?
Answer
(D)
X (g) → X+ (g) +e-
26
What is the molar of hydrogen sulphide gas in the reaction H2SO4(aq) + 3H2S(g) → 4S(s) + 4H2O (l)n represented by the following equation?
Answer
(A)
Reducing agent
27
Alkanols have unexpectedly high boiling points relative to their molar masses because of intermolecular
Answer
(A)
hydrogen bonding
28
Sodium chloride is used in the following processes except in the
Answer
(A)
treatment of polluted water
29
The gaseous product formed when ammonia is passed over heated copper (ll) oxide is
Answer
(B)
nitrogen
30
Which of the following is not a halogen?
Answer
(A)
Silicon
31
Which of the following is likely to have the highest degree of hardness?
Answer
(E)
Lime water
32
Study the reaction represented by the equation: Alkanol + Alkanoic acid + conc. H\(_2\)SO\(_4\) → Alkanoate + water.  The type of process involved in the reverse reaction is
Answer
(C)
hydrolysis
33
Destructive distillation of coal means
Answer
(C)
heating coal in the absence of air
34
When magnesium ribbon burns in air, the products are
Answer
(C)
magnesium oxide and steam
35
The following compounds contain the same type of bonds except
Answer
(B)
hydrogen chloride