WAEC - Chemistry (2021)

1
The hydrolysis of proteins by diluting mineral acids produces
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(C)
amino acids
2
Which of the following oxide causes acid rain?
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(D)
NO\(_{2}\)
3
The ratio of carbon atoms of hydrogen atoms in a hydrocarbon is 1:2. If its molecular mass is 56, what is its molecular formula?
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(B)
C\(_{4}\)H\(_{8}\)
4
What is the relative molecular mass of the compound below?

[H = 1.0; C = 12.0; O = 16.0]
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(B)
136
5
Cathodic protection of metals is based on
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(D)
relative tendencies of oxidation
6
If humid air is polluted by chlorine discharged, the air can be restored by sprinkling
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(B)
acidified KMnO\(_{4}\)
7

The alkanol represented by the structure above is
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(A)
primary and dihydric
8
Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?
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(C)
K\(_{2}\)SO\(_{4}\) and BaCl\(_{2}\)
9
Which of the following illustrates the variation of the rate of evolution of gas from a given length of magnesium ribbon (y-axis) with an increase in the concentration of the added (x-axis)?
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(A)
I
10
Which of the graphs illustrates the variation of the pH of a given volume of strong acid solution (y-axis) with the volume of strong base titrated against its (x-axis)?
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(A)
I
11
Which of the graphs illustrates the variation of the solubility of a salt in water (y-axis), with an increase in temperature (x-axis) if the dissolution process is exothermic?
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(D)
IV
12
The formation of ethene from dehydration of ethanol can be described as-------
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(B)
an elimination reaction
13
Which of the following gasses is highly soluble in water at room temperature
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(A)
ammonia
14
A molecular of phosphorus is
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(C)
tetraatomic
15
The most common method of preparing insoluble salts is by
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(D)
double decomposition
16
What number of moles of oxygen would exert a pressure of 10 atm at 320 K in an 8.2 dm\(^{2}\) cylinder?

[R = 0.082 atm dm\(^{3}\) mol\(^{-1}\) K\(^{-1}\)]

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(C)
3.13
17
The basic property of salts used as drying agents is by?
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(C)
hygroscopy
18
What would be observed when aqueous ammonia is added in drops and then in excess to a solution of copper(II) ions?
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(A)
blue precipitate is formed which is soluble in excess ammonia
19
When CuSO\(_{4(aq)}\) is added to Pb(NO\(_{3}\))\(_{2(aq)}\)--------
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(D)
a white precipitate would be formed
20

Consider the structure above

How many carbon atoms does the parent chain contain?
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(B)
4
21
Under which conditions of pressure (p) and temperature (T) would the volume of an inflated ballon increase? When
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(C)
T is increased and P is decreased
22
The collision between ideal gas molecules are considered to be perfectly elastic because
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(A)
they collide without losing energy
23
Elements with high ionization energies would-------
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(C)
have high effective nuclear charges
24
Which of the following statements about Group VII elements is correct?
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(C)
their reactivity decreases down the group
25
Which of the following cell notations represent the diagram
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(D)
A/A\(^{3+}\)/ /B\(^{2+}\)/B
26
Which of the following half reaction equations represent the reaction at the cathode
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(B)
B\(^{2+_{(aq)}}\)+2e\(^{-}\) \(\rightarrow\) B\(_{(s)}\)
27
The reactivity of fluorine is high because of
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(A)
its high electronegativity
28
How many coulombs of electricity would liberate 1.08g of Ag from a solution of silver salt?

[Ag = 108.0; 1F = 96500 C]
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(C)
965 C
29
The Bohr model of the atom proposed the existence of?
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(B)
electron shells
30
The 25°C evaporation of a 100 cm\(^{3}\) solution of K\(_{2}\)CO\(_{3}\) to dryness gave 14g of the salt. What is the solubility of K\(_{2}\)CO\(_{3}\) at 25°C? [K\(_{2}\)CO\(_{3}\) = 138]
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(C)
1.01 mol dm \(^{-3}\)
31
Student X titrated 25 cm\(^{3}\) of Na\(_{2}\)CO\(^{3}\) with 0.1 mol dm\(^{-3}\) HCI, using methyl orange as indicator. Student Y carried out the same exercise but used phenolphthalein as an indicator. Which of the following statements about the titration is true?
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(B)
the titer values obtained from the titration are equal
32
What is the concentration of a solution which contains 0.28g of potassium hydroxide in 100 cm\(^{3}\) of solution [KOH = 56]
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(B)
0.05 mol dm\(^{-3}\)
33
What is the empirical formula of a hydrocarbon containing 0.160 moles of carbon and 0.640 moles of hydrogen
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(C)
CH\(_{4}\)
34
Which of the following species has the largest ionic radius
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(A)
S\(^{2-}\)
35
Which of the following statements is correct about ionization energy? It
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(D)
decreases down the group
36
Potassium trioxonitrate (V) can be obtained from its solution by----------
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(C)
crystallization
37
An element, Q, contains 69% of\(^{63}\)Q and 31% of \(^{65}\)Q. What is the relative atomic mass of Q?
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(B)
63.6
38
The following ions have the same electron configuration except

\(_{8}\)O, \(_{12}\)Mg, \(_{13}\)AI, \(_{17}\)CI
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(A)
CI\(^{-}\)
39
The region around the nucleus where electrons can be located is called?
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(B)
an orbital
40
Protons and electrons are called fundamental particles because they----------
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(D)
are found in all matter
41
The activation energy of the reaction is
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(C)
E\(_{C}\)
42

The enthalpy change of the reaction is------------
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(D)
E\(_{D}\)
43
The energy profile diagram illustrates-------------
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(B)
an exothermic reaction
44
How many molecules of oxygen would occupy a volume of 2.24 cm\(^{3}\) at s.t.p?

[Molar volume at s.t.p = 22,400 cm\(^{3}\), Avogadro's number = 6.02 x 10\(^{23}\)]
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(C)
6.02 x 10\(^{19}\)
45
The isotopes of neon are represented by the symbols \(^{20}\)\(_{x}\) Ne, \(^{21}\) \(_{y}\) Ne, and \(^{22}\) \(_{z}\) Ne. The relationship between x, y, and z is?
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(C)
x = y= z