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Physics WAEC / WASSCE 2021 Electricity and Magnetism
(a) You are provided with a battery, an ammeter, a voltmeter, a resistance box, a key and connection wires. (i) Set up circuit as shown in the diagram above. (ii) With the key opened, measure and record the e.m.f. E\(_o\) of the battery (iii) With the key closed, select the resistance R=1 on the resistance box. Read and record the current, 1\Omega. (iv) Evaluate I\(^{-1}\). (v) Repeat the procedure for five other values of R=2\Omega,3\Omega, 4\Omega, 5\Omega, and 6\Omega. In each case, record I and evaluate I\(^{-1}\) results. (vii) Plot a graph with R on the vertical axis and I\(^{-1}\) on the horizontal axis. (Viii) Determine the slope, s, of the graph. (ix) Determine the intercept C, On the vertical axis. (x) State two precautions taken to ensure accurate results. (b)(i) Define potential difference in an electric field. (ii) A piece of resistance wire of diameter 0.2 mm and length 25 cm has a resistance of 7\Omega. Calculate the resistivity of the wire of the battery. [ \pi = 22\7]
Attached Figure / Diagram
Question diagram
medium Difficulty
Physics WAEC / WASSCE 2021 Heat Energy & Temperature
(a) You are provided with a battery, an ammeter, a voltmeter, a resistance box, a key and connection wires. (i) Set up circuit as shown in the diagram above. (ii) With the key opened, measure and record the e.m.f. E\(_o\) of the battery (iii) With the key closed, select the resistance R=1 on the resistance box. Read and record the current, 1Ω. (iv) Evaluate I\(^{-1}\). (v) Repeat the procedure for five other values of R=2Ω,3Ω, 4Ω, 5Ω, and 6Ω. In each case, record I and evaluate I\(^{-1}\) results. (vii) Plot a graph with R on the vertical axis and I\(^{-1}\) on the horizontal axis. (Viii) Determine the slope, s, of the graph. (ix) Determine the intercept C, On the vertical axis. (x) State two precautions taken to ensure accurate results. (b)(i) Define potential difference in an electric field. (ii) A piece of resistance wire of diameter 0.2 mm and length 25 cm has a resistance of 7Ω. Calculate the resistivity of the wire of the battery. [ \pi = 22\7]
A
Isaac Newton
B
Ernest Rutherford
C
Louis de Broglie
D
J.J. Thompson
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
The hydrolysis of proteins by diluting mineral acids produces
A
sucrose
B
glucose
C
amino acids
D
fatty acids
medium Difficulty
Chemistry WAEC / WASSCE 2021 Stoichiometry & Mole Concept
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?
A
\(C_3\)\(H_6\)
B
\(C_4\)\(H_8\)
C
\(C_2\)\(H_4\)
D
C\(H_2\)
medium Difficulty
Chemistry WAEC / WASSCE 2021 Stoichiometry & Mole Concept
What is the relative molecular mass of the compound below? [H = 1.0; C = 12.0; O = 16.0]
A
137
B
136
C
64
D
59
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
Cathodic protection of metals is based on
A
standard electrode potential of hydrogen
B
its electrical conductivity
C
nature of oxides formed
D
relative tendencies of oxidation
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
If humid air is polluted by chlorine discharged, the air can be restored by sprinkling
A
solid Mn\(O_2\)
B
acidified KMn\(O_4\)
C
acidified FeS\(O_4\)
D
saturated NaCl(aq)
medium Difficulty
Chemistry WAEC / WASSCE 2021 Matter & Separation Techniques
Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?
A
NaCl and KN\(O_3\)
B
KCL and NaN\(O_3\)
C
\(K_2\)S\(O_4\) and BaC\(l_2\)
D
N\(H_4\)N\(O_3\) and C\(O_3\)
medium Difficulty
Chemistry WAEC / WASSCE 2021 Matter & Separation Techniques
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)?
A
I
B
II
C
III
D
IV
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
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)?
A
I
B
II
C
III
D
IV
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
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?
A
I
B
II
C
III
D
IV
medium Difficulty
Chemistry WAEC / WASSCE 2021 Matter & Separation Techniques
The formation of ethene from dehydration of ethanol can be described as-------
A
an addition reaction
B
an elimination reaction
C
an oxidation reaction
D
a substitution reaction
medium Difficulty
Chemistry WAEC / WASSCE 2021 Matter & Separation Techniques
Which of the following gasses is highly soluble in water at room temperature
A
ammonia
B
carbon (IV) oxide
C
chlorine
D
nitrogen
medium Difficulty
Chemistry WAEC / WASSCE 2021 Stoichiometry & Mole Concept
A molecular of phosphorus is
A
diatomic
B
triatomic
C
tetraatomic
D
monoatomic
medium Difficulty
Chemistry WAEC / WASSCE 2021 Acids, Bases, and Salts
The most common method of preparing insoluble salts is by
A
filtration
B
decomposition
C
neutralization
D
double decomposition
medium Difficulty
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