WAEC - Chemistry (2007)

1
When sodium atom form the ion Na+,
Answer
(B)
it achieves a noble gas configuration
2
Which of the following statements about rare gases are correct?
Answer
(A)
Their outermost shells are fully filled
3
Which of the following properties is characteristic of the halogens?
Answer
(A)
Ability to accept electrons readily
4
In which of the following atoms is the ionic radius larger than the atomic radius? [11 Na, 12Mg,13AI,17CI]
Answer
(B)
Chlorine
5
A transition metal would be expected to
Answer
(A)
from oxides with different formulae
6
Which of the following properties of atoms generally increases down a group in the periodic table?
Answer
(C)
Ionic radius
7
Which of the following statements about sodium is not true?
Answer
(B)
Na is smaller in size than Na+
8
If the difference between the electronegativities of two elements is large, the type of bond that can be formed between them is
Answer
(C)
ionic
9
Which of the following compounds has hydrogen bonds between its molecules?
Answer
(A)
HF
10
Which of the following species does not contain a co-ordinate bond?
Answer
(A)
AI2CI6
11
14.8 g of a salt (z)dissolved in 250 cm3 of distilled water gives a concentration of 0.80 mol dm-3. Calculate the molar mass of the salt (z).
Answer
(D)
74.0 g mol-1
12
How many atoms are there in one mole of hydrogen gas? [Avogadro's constant = 6.02 x 1023mol-1]
Answer
(C)
1.2 x10 24
13
What is the IUPAC name of the compound represented by the molecular formula NaCIO4?
Answer
(D)
Sodium tetraoxochlorate(VII)
14
When air is successively passed through sodium hydroxide solution, alkaline pyrogallol and then concentrated tetraoxosulphate (VI) acid, its remaining components are
Answer
(D)
nitrogen and noble gases
15
Which of the following gases is light than air?
Answer
(D)
NH3
16
Which of the following statements is true of the molecules of a gas under ideal conditions? The molecules
Answer
(A)
move at random
17

In which of the following compound (s) will heat be absorbed on adding water?

l. KNO\(_3\) II. Concentrated H\(_2\)SO\(_4\) III. NH\(_4\)CI

Answer
(C)
l and lll only
18
Consider the reaction represented by the equation: Ca(OH)2(aq) + CO 2(g) → CaCO3(s) + H 2O(l)
in the reaction above, CO 2 acts as
Answer
(A)
an acidic oxide
19
Which of the following compounds is a basic salt?
Answer
(D)
Zn(OH)CI
20
What process is illustrated below? S(s) ⇌H2O⇌ S (aq)
Answer
(C)
Formation of saturated solution of a solid
21
A solution of a salt X reacts with AgNO3 solution to give white precipitate which dissolves in excess aqueous ammonia. X contains
Answer
(A)
CI-
22
Consider the reaction represented by the following equation: N2(g) + 3H2(g) ⇌ 2NH3(g); ∆H = - 92kJmol1. Finely divided iron is used as catalyst in the reaction in order to
Answer
(C)
shorten the time for attainment of equilibrium
23
Which of these cell notations is the correct representation of a Daniell cell?
Answer
(A)
Zn(s) / Zn2+(aq) // Cu2+(aq)/Cu(s)
24
What is the oxidation number of chromium in K2CrO4?
Answer
(D)
+6
25
What product is formed at the cathode during the electrolysis of concentrated sodium chloride solution using carbon electrodes?
Answer
(B)
Hydrogen
26
Which of the following substances is suitable solvent for perfumes?
Answer
(B)
Ethanol
27
The complete hydrogenation of C 6
H 6 in the presence of nicked catalyst at 200oC gives
Answer
(C)
C 6H 12
28
Which of the following pairs of substances can be distinguished by use of NaHCO3 solution?
Answer
(B)
CH 3CH2OH and CH3COOH
29
Alkenes undergo the following reactions except
Answer
(D)
substitution
30
Hydrocarbons which react with ammoniacal copper (l) chloride solution conform to the general molecular formula
Answer
(D)
CnH2n-2
31
Consider the reaction below: Vegetable oil \(\frac{H2;NI catalyst}{High temperature}\) product. The reaction is applied in the manufacture of?
Answer
(B)
margarine
32
Which of the following compounds reacts readily with sodium to liberate hydrogen?
Answer
(B)
CH3COOH
33
Glucose reduces Fehling's solution on warming to
Answer
(A)
copper (l) oxide
34
from the following ores is iron extracted? I. Haematite ll. Bauxite III. Magnetite IV. Cassiterite
Answer
(B)
l and lll only
35
Which of the following methods can be used to separate a mixture of two miscible liquids with different boiling points?
Answer
(B)
Distillation