Which of the following is not a safety precaution in a nuclear station?
ARadioactive materials are stored in glass casings
BRadioactive materials are handled with remote-controlled tongs
CTechnicians in nuclear stations wear radio-sensitive badges which are checked regularly.
DRadioactive materials are kept in thick-walled lead containers
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Question 2
waec1999
Which of the following are the essential parts of an atomic bomb?
AUranium and neutrons
BRadium and polonium
CNitrogen and neutrons
Dranium and α - particles.
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Question 3
waec1999
A sheet of paper is placed in the path of the following radiations: I. Alpha particles II. Beta particles III. Gamma rays. Which of the radiations will pass through the sheet of paper?
AI only
BII only
CI and II only
DII and III only
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Question 4
waec1999
The half-life of a radioactive element is 5 Calculate its decay constant
A0.113s-1
B0.436 s-1
C0.139 s-1
D0.193 s-1.
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Question 5
waec1999
The half-life of a radioactive substance is
Aits average life time
Bone-half the value of its decay constant.
Cthe length of time needed by the substance to decay completely
Dthe length of time during which the activity of the substance reduces by 50%.
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Question 6
waec1999
A metal has work function of 4.375 eV Calculate its threshold frequency. (h = 6.6 x 10-34Js; 1eV = 1.6 x 10-19J)
A2.01 X 1015Hz
B1.06x1015Hz
C6.30 x 1014Hz
D1.60 x 1014Hz
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Question 7
waec1999
I. All elements emit and absorb characteristic spectra. II. Spectral analysis is an important method of identifying environmental pollutants. III. The chemical composition of stars could be determined using spectral analysis. Which of the statements above are correct?
AI, II and III
BII and III only
CI and III only
DI and II only
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Question 8
waec1999
Which of the transitions will produce the emission of highest frequency?
AV
BIV
CIII
DII
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Question 9
waec1999
The diagram above illustrates the energy transitions of five electrons of an atom. Which of the transitions will produce the emission of longest wavelength?
AI
BII
CIII
DIV
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Question 10
waec1999
Bohr’s atomic model proves most successful for the explanation of the. I. structure of the hydrogen atom; II. line spectra of the hydrogen atom; III. Multi-electron atoms. Which of the statements above is/are correct?
AI only
BII only
CI and II only
DI and III only
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Question 11
waec1999
A point charge of magnitude 2μC is moved through a distance of 0.02 m against uniform field of intensity 25 Vm-1 Calculate the work done on the charge
A5.0 x 106J
B1.0 x10-6J
C5.0 x10-7J
D1.0 x 10-2J
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Question 12
waec1999
A 10 Ω coil takes 21 s to melt 10g of ice at 0ºC. Assuming no heat losses, determine the current in the coil. (Specific latent heat of fusion of ice = 336 Jg\(^{-1}\))
A16A
B5A
C4A
D3A
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Question 13
waec1999
In a uniform electric field, the magnitude of the force on a charge of 0.2 C is 4N. Calculate the electric field intensity
A20 N C-1
B8 N C-1
C5 N C-1
D2 N C-1
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Question 14
waec1999
The voltage and current in the primary of a transformer are 200V and 2Arespectively. lf the transformer is used to light ten 12 V, 30 W bulbs, calculate its efficiency.
A100%
B90%
C75%
D50%
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Question 15
waec1999
Magnetic flux density is defined as the
Atotal number of magnetic lines of force surrounding a magnet
Bnumber of magnetic lines of force per unit area normal to the magnetic field
Cstrength of the magnetic field surrounding a current-carrying conductor
Dmagnetic force exerted on a unit magnetic pole
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Question 16
waec1999
A resistance wire of length 2 m and of uniform cross-sectional area 5.0 x 10-7 m2 has a resistance of 2.2 Ω Calculate its resistivity
A1.8 x 10-7Ωm
B5.5 x 10-7Ωm
C1.8 x 10-7Ωm
D5.8 x 107Ωm
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Question 17
waec1999
The parts of a bar magnet at which the magnetic effect is strongest are called the
Apoles
Bneutral points
Cmagnetic declinations
Dmagnetic meridians
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Question 18
waec1999
Using the diagram above, calculate the effective capacitance of the circuit
A1.56μf
B3.00μF
C3.71μF
D9.00μF
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Question 19
waec1999
Using the data on the diagram above, calculate the potential difference across the 20- Ω resistor. (Neglect the internal resistance of the cell)
A5V
B10V
C20V
D60V
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Question 20
waec1999
Thunder is usually heard some seconds after lightning is observed because
Athe human eye is more sensitive to light than the ear to sound
