Which of the following are emitted from a radioactive substance without altering either the nucleon number or the proton number of the substance?
AGamma rays
BAlpha particles
CBeta particles
DProtons
ENeutrons
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Question 792
waec1993
When an atom is in the ground state, it is said to be
Agrounded
Bexcited
Cstable
Dionized
Eradiating
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Question 793
waec1993
Eight or - particles and size B - particles are emitted from an atom of 92238U before it achieves stability. What is the nucleon number of the final product in the chain reaction?
A206
B234
C238
D240
E252
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Question 794
waec1993
According to the kinetic theory of gases the collision
of the molecules of a gas with the wall of the container
is mainly responsible for the l. temperature of the
gas ll. viscosity of the gas Ill. pressure of the gas
Which of the statements above is/are correct?
AI only
BII only
CIII only
DII and III only
EI, II and III.
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Question 795
waec1993
Which of the following is used a nuclear reactor to slow down fast moving neutrons?
ACarbondioxide gas
BLiquid sodium metal
CConcrete shield
DGraphite rods
EBoron rods
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Question 796
waec1993
A radioactive substance has a half-life of 20 hours. What fraction of the original radioactive nuclide will remain after 80 hours?
A1/32
B\(\frac{1}{16}\)
C\(\frac{1}{8}\)
D\(\frac{1}{4}\)
E\(\frac{1}{2}\)
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Question 797
waec1993
The phenomenon of radioactivity was first discovered by
AMarie Curve
BSir J.J Thomson
CHenn Becquerel
DNiels Bohr
EEnrico Fermi
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Question 798
waec1993
lf Einstein’s photoelectric equation is represented by hf - W = Φ where h is Planck’s constant, f the frequency of incident radiation and W the work function of the material, what does the symbol Φ up stand for?
AEnergy of the photons
BMaximum Kinetic energy of the ejected electrons
CThreshold frequency of the photons
DStopping potential of the electrons
EVelocity of the electrons
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Question 799
waec1993
24 Na →
24 mg4 + X + energy
11
2
The equation above represents a nuclear decay of sodium isotope. What is X?
AAlpha particle
BBeta particle
CGamma ray
DX-ray
ENeutron
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Question 800
waec1993
How long does it take a 750 W heater operating at full rating to raise the temperature of 1 kg of water from 40oC to 70oC? (Take the specific heat capacity of water as 4200 J kg-1 K-1 and neglect heat losses).
A84s
B112s
C168s
D280s
E616s
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Question 801
waec1993
What amount of current would pass through a 10 Ω coil if it takes 21s for the coil to just melt a lump of ice of mass 10g at 0oC if there are no heat losses? (Latent heat of fusion of ice = 336 Jg\(^{-1}\)).
A16.00A
B4.00 A
C0.50A
D0.25A
E0.06 A
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Question 802
waec1993
Electric motor primarily converts
Aelectrical energy into chemical energy
Belectrical energy into heat energy
Ckinetic energy into potential energy
Delectrical energy into mechanical energy
Emechanical energy into light energy
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Question 803
waec1993
When a potential difference, V is applied across the ends of a resistor of resistance, R a Current, l passes through the resistor. The heat generated in the resistor in time, t is given by the expression
AV2lt
BI2t/R
Cl2Rt
DlR2tR
EV2Rt
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Question 804
waec1993
ln the diagram below, the galvanometer indicates a null-deflection. What is the potential difference between P and Q?
A0.0 V
B1.5 V
C2.0 V
D3.0V
E4.0 V.
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Question 805
waec1993
Which of the following is not a conductor of electricity?
AHuman body
BGlass
CSilver
DEarth
ECopper
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Question 806
waec1993
Calculate the current, I in the diagram shown above.
(Neglect the internal resistance of the cell)
A4.0A
B2.0A
C1.0A
DO.5A
E0.1A.
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Question 807
waec1993
Electrical resistance is the property of an electrical conductor that causes electrical energy to be converted into
Amechanical energy
Bsolar energy
Cheat energy
Dmagnetic energy
Echemical energy.
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Question 808
waec1993
In the diagram above, three identical lamps each of 100 W are connected in parallel across a potential difference of 250 V. Calculate the reading of the ammeter.
A7.5A
B2.5A
C1.2A
D0.8A
EO.4A
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Question 809
waec1993
The function of the magnanese (IV) oxide in a leclanche cell is to
Adecrease the e.m.f. of the cell
Bprevent local action in the cell
Cprevent polarization in the cell
Dincrease the density of the electrolyte
Eincrease the resistance of the cell.
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Question 810
waec1993
A particle of charge 5C moves perpendicularly to a magnetic Held of magnitude C.01 T. If the velocity of the charge is 1.5ms'2, calculate the magnitude of the force exerted on the particle
