2003 - WAEC Physics Past Questions and Answers - page 5

41
A radioactive element has a decay constant of 0.077s-1, calculate its half life
A
12.5s
B
9.0s
C
5.1s
D
0.5s
correct option: b
T = \(\frac{0.692}{\lambda} = \frac{0.692}{0.077}\)

= 9s
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42
The minimum energy required to remove an electron from an atom is known as
A
excitation energy
B
ionization energy
C
binding energy
D
photon energy
correct option: b
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43
Nuclear fission is preferred to nuclear fusion in the generation of energy because
A
very high temperature are required for fusion
B
the raw material of fusion are not easily obtained
C
energy obtained from fusion is relatively smaller
D
the by product of fusion are very dangerous
correct option: c
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44
Which of the following reactions represents nuclear fusion?
A
\(^2_1H + ^2_1H \to ^3_2He + ^1_0n\)
B
\(^235_92U + ^1_0n \to ^145_56Ba + ^90_36Kr \)
C
\(^234_90TH \to ^0_-1n + ^3_2He + ^1_0Pa\)
D
\(^238_92U \to ^4_2H \to ^3_2He + ^234_90Th\)
correct option: a
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45
The diagram above shows the resultant electric field pattern due to two electric point charges P and S. Which of the following statements is correct?
A
P is negatively charged while S is positively charged
B
P is positively charged while S is negatively charged
C
both P and S are positively charge
D
both P and Q are negatively charged
correct option: d
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46
The bar magnet illustrated in the diagram above picks up an unmagnetised steel nail X. In turn, X picks up a similar nail Y and so on. The nail are said to be magnetised by
A
conduction
B
single touch
C
induction
D
divided touch
correct option: c
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