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WAEC - Chemistry (2005)

1
The electronic configuration of an element X is 1s22s 22s63p 2 3p4. It can be deduced that X
Answer
(A)
Belongs to group 6 of the Periodic Table
2
What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?
Answer
(C)
35
3
Which of the following sets of elements are arranged in order of decreasing atomic size in the Periodic Table?
Answer
(B)
4Be,6 C,7 N,8 O
4
Which of the following changes is characteristic of an alpha-particle emission?
Answer
(A)
the nucleus loses two protons and two neutrons
5
An element X has an atomic number of 16. What is its most likely oxidation state in its binary compounds?
Answer
(B)
-2
6
An element which can exist in two or more forms in the same physical state, exhibits
Answer
(C)
allotropy
7
Which of the following can be used to predict the type of bonding in HCI?
Answer
(B)
Electronegativity difference
8
Which of the following molecules has a linear structure?
Answer
(C)
CO2
9
The volume occupied by a given mass of gas depends on its
Answer
(B)
temperature and pressure
10
In which of the following reactions is the position of equilibrium not affected by an increase in pressure?
Answer
(A)
3Fe(s) + 4H2O(g) ⇌ Fe3O4(s) + 4H2(g)
11
The activation energy of a reaction can be altered by
Answer
(C)
using a catalyst
12
Which of the following factors does not affect the rate of reaction of CaCO3 with HCI?
Answer
(B)
solubility of the CaCO3
13
When X is heated with manganese (IV) oxide, oxygen is produced X is
Answer
(B)
KCIO3
14
Which of the following statements is not a postulate of the kinetic theory of gases?
Answer
(A)
Molecules move with the same speed
15
HNO3 does not usually react with metals to liberate hydrogen because HNO3 is
Answer
(C)
an oxidizing agent
16
Which of the following is not an acid anhydride?
Answer
(D)
CO
17
NaHCO3(s) can be distinguished from Na2CO3(s) by the action of
Answer
(D)
heat
18
What process is involved in the reaction represented by the following equation? AICI3 + 3H2O(l) → AI(OH) 3(s) + 3HCI(g)
Answer
(B)
hydrolysis
19
A salt that absorbs moisture from the atmosphere without forming a solution is said to be
Answer
(C)
hygroscopic
20
Consider the reaction represented by the equation below, xNH3(g) + yCI2(g) → zHCI(g) + N2(g) The values of x,y and z are respectively
Answer
(C)
2, 3, 6
21
Which of the following compounds dissolves readily in water?
Answer
(C)
NH4CI
22
When ice is changing to water, its temperature remains the same because the heart gained is
Answer
(A)
used to separate the molecules
23
Which of the following methods is suitable for preparing insoluble salts?
Answer
(C)
Double decomposition
24
Which of the following reactions is sulphur (IV) oxidizing agent?
Answer
(B)
2KMnO 4(aq) + 5SO2(g) + 2H2O → K2SO4(aq) +MnSO4(aq) 2H2SO4(aq)
25
Which of the elements will burn in excess oxygen to form a product that is neutral to litmus?
Answer
(B)
Hydrogen
26
The main difference between a primary cell and a secondary cell is that the primary cell
Answer
(B)
cannot be recharged but the secondary cell can
27
Determine the mass of copper deposited by 4.0 moles of electrons in the reaction represented by the equation below: Cu2(aq) + 2e- → Cu(s)
Answer
(C)
128
28
Reaction undergone by compounds with the general formula Cn H2n+2 include
Answer
(C)
substitution
29
What is the major product formed when C2H5OH reacts with CH3COOH?
Answer
(C)
CH3COOC2H5
30
Which of the following substances is a non-reducing sugar?
Answer
(A)
Sucrose
31
The colour of the solution formed when ethyne reacts with an acidic solution of potassium tetraoxomanganate (VII) is
Answer
(B)
colourless
32
Fats are classified as
Answer
(B)
alkanoates
33
Ethyne undergoes the following reactions except
Answer
(D)
esterification
34
Hardness in water can be removed by adding
Answer
(B)
sodium trioxocarbonate (IV)
35
Which of the following pairs of solutions will produce a precipitate when mixed?
Answer
(A)
Pb(NO3)2(aq) and NaCI(aq)