An electric heater is used to melt a block of ice of mass 1.5kg. If the heater is powered by a 12V battery and a current of 20A flows through the coil, calculate the time taken to melt the block of ice at 0oC. [specific latent heat of fusion of ice = 336 x 103Jkg-1]
A76.0min
B35.0min
C21.0min
D2.9min
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Question 2072
jamb1989
A mass of gas at 7oC and 70cm of mercury has a volume of 1200cm3. Determine its volume at 27oC and pressure of 75cm of mercury.
A1200cm3
B1378cm3
C4320cm3
D4629cm3
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Question 2073
jamb1989
A column of air 10.0cm long is trapped in a tube at 27oC. What is the length of the volume at 100oC?
A12.4cm
B13.7cm
C18.5cm
D37.0cm
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Question 2074
jamb1989
The pressure on the gas of constant gas thermometer at the ice point is 325mm of mercury and at the steam point is 875mm of mercury. Find the temperature when the pressure of the gas is 190mm of mercury
A30k
B243k
C300k
D3003k
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Question 2075
jamb1989
A piece of wood of mass 40g and uniform cross-sectional area of 2cm2 floats upright in water. The length of the wood immersed is
A30cm
B40cm
C20cm
D2cm
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Question 2076
jamb1989
Which of the following devices are used to measure pressure? i. Aneroid barometer. ii. hydrometer. iii. hygrometer. iv. manometer.
Ai and iii
Bii and iii
Ciii and iv
Di and iv
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Question 2077
jamb1989
A block-and-tackle system is used to lift a load of 20N through a vertical height of 10m. if the efficiency of the system is 40%, how much work is done against friction?
A80J
B120J
C300J
D500J
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Question 2078
jamb1989
A thin film of liquid is trapped between two glass plates. The force required to pull the plates apart will increase if the
Asurface tension of the liquid is reduced
Bperpendicular distance between the plates is increased
Carea of the liquid surface in contact with the plates is increased
Dpressure of the air is decreased
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Question 2079
jamb1989
Two points on a velocity time-graph have coordinates (5s, 10ms-1) and (20s, 20ms-1). Calculate the mean acceleration between the two points
A0.67ms-1
B0.83ms-1
C1.50ms-1
D2.00ms-1
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Question 2080
jamb1989
The magnitude of the resultant of two mutually perpendicular forces, F1 and F2 is 13N, if the magnitude of F1 is 5N, what is the magnitude of F2?
A2.6N
B6.0N
C12.0N
D18.0N
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Question 2081
jamb1989
Which of the following is a set of vectors?
Aforce, mass and moment
Bacceleration, velocity and moment
Cmass, weight and density
Dmass, volume and density
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Question 2082
waec1988
During the same interval, it is observed that a train travels the same distance as does a lorry. The two vehicles therefore have the same
Auniform accelation
Binstateneous velocity
Cinitial velocity
Daverage speed
Eaverage velocity
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Question 2083
waec1988
Two radioactive elements A and B have half-lives of 100 and 50 years respectively. Samples of A and B initially contain equal amounts/number of atoms. What is the ratio of the number of the remaining atoms of A to that of B after 200 years?
A4 : 1
B2 : 1
C1 : 1
D1 : 2
E1 : 4
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Question 2084
waec1988
Which of the following is not an electromagnetic radiation?
AX-ray
BRadio waves
CSunlight
DSound waves
EInfra-red radiation
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Question 2085
waec1988
An electron of charge 1.6 x 1019C is accelerated in vacuum from rest at zero volt towards a plate of 40KV. Calculate the kinetic energy of the electron.
A4 x 10 25J
B4 x 1021 J
C6.4 x 1020 J
D6.4 x 10-15 J
E2.5 x 1020 J
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Question 2086
waec1988
Which of the following is/are not affected by a magnetic field?
I. Neutrons
II. Cathode rays
III. Alpha particles
AI only
BII only
CIII only
DI & III only
EI, II & III
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Question 2087
waec1988
Which of the following is/are not correct about isotopes of an element? The have
Athe same neutron number
Bthe same proton number
Csame number of electrons
Dsame chemical properties
Edifferent physical poperties.
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Question 2088
waec1988
The unit of inductance is the
Afarad
Bhenry
Chertz
Dampere
Ecoulomb
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Question 2089
waec1988
Which of the following explains the concave meniscus of water in a glass tube?
AThe adhesion between water and glas is greater than the cohesion between water molecules
BThe cohesion between water molecule is greater than the adhesion between glass and water
CThe molecules of water in the glass are moving faster than the molecules in the other parts
DThe molecules of water at the water-air boundary are often attracted to the center of the tube
EThe weight of the water pulls the central part of the surface down
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Question 2090
waec1988
When sugar at the bottom of a glass of water gradually dissolves, the water level does not change applicably. Which of the following statements best describe this?
AWater is suitable solvent for sugar
BThe sugar and the water have become single solution
CThe volume of water molecule does not change when sugar dissolves.
DSugar molecule is small than that of water
EWater molecules are separated by large spaces between them
