Multiple choice question for engineering
1. Which one of the following is the property of an ionic compound?
a) High melting and boiling points
b) Low melting and boiling points
c) Weak inter-atomic forces
d) Non conductors of electricity
Answer: a [Reason:] Ionic compounds are very strong in nature. They require a lot of energy to break them. Therefore they have high melting and boiling points.
2. When do ionic compounds conduct electricity?
a) In gaseous state
b) In solid state
c) When dissolved in water
d) They never conduct
Answer: c [Reason:] Ionic compounds can conduct electricity only if their ions are free to move. Hence they behave as conductors when they are dissolved in water.
3. Which of the following covalent compounds conduct electricity?
d) Hydrogen chloride
Answer: b [Reason:] Graphite is made up of carbon layer that can slide over each other. Like metals, the electrons are free to move. Whereas, the rest of the compounds are made up of carbon atoms held together tightly. Therefore, graphite is the covalent compound that conducts electricity.
4. Which of the following is a crystalline solid?
a) Anisotropic substances
b) Isotropic substances
c) Supercooled liquids
d) Amorphous solids
Answer: a [Reason:] Crystalline solids are those in which atoms are arranged in an orderly fashion. They have directional properties and therefore are called anisotropic substances
5. Why are the glasses of building milky?
a) Because of unwanted deposits
b) Because it becomes old
c) Because it is brittle
d) Because it changes in properties
Answer: d [Reason:] Glasses of building appear milky because it undergoes heating during the day and cooling during night. Therefore it acquires some crystalline properties
6. Which of the following has body centred cubic structure?
Answer: d [Reason:] In tungsten, atoms are arranged in all eight corners and has an additional atom in the centre satisfying the body centred cubic lattice condition.
7. What is the possible number of different types of lattices (3D)?
Answer: c [Reason:] According to Bravis, there are only 14 possible ways of arranging points in space lattice from the 7 crystal systems such that, all the lattice points have exactly the same surrounding.
8. What is the lattice constant for FCC crystal having atomic radius 1.476 Å
a) 1.476 Å
b) 4.1748 Å
c) 5.216 Å
Answer: b [Reason:] Radius=1.476 Å or 1.476 × 10-10 m
Lattice constant for FCC = 4r/√2
Lattice constant = 4.1748 Å
9. The interplanar spacing of (220) planes of a FCC structure is 1.7458 Å. Calculate the lattice constant.
a) 4.983 Å
b) 2.458 Å
d) 5.125 Å
Answer: a [Reason:]
D = 1.7458 Å = 1.7458 × 10-10 m
h = 2; k = 2; l = 0
a = 4.983 Å
10. Iron has a BCC structure with atomic radius 0.123 Å. Find the lattice constant.
b) 4.587 Å
c) 2.314 Å
d) 0.2840 Å
Answer: d [Reason:] r = 0.123 Å
The lattice constant for BCC = 4r/√3
The lattice constant = 0.2840 Å
1. A body can have momentum without energy. True or false?
Answer: b [Reason:] If a body has momentum, it must be in motion and consequently possess kinetic energy. Therefore a body cannot have momentum without energy.
2. Comets mover around the sun in a highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet’s velocity in general. Yet the work done by the gravitational force over every orbit of the comet is zero. Why?
a) The gravitational force is conservative, hence work done is zero
b) The gravitational force is non-conservative, hence work done is zero
c) Energy is absent, hence work done is zero
d) Force is in negative direction
Answer: a [Reason:] The gravitational force acting on the comet is a conservative force. The work done by a conservative force is equal to the negative of the change in potential energy. Over a complete orbit of any shape, there is no change in potential energy of the comet. Hence no work is done by the gravitational force on the comet.
3. An artificial satellite orbiting the earth in very thin atmosphere loses its energy gradually due to dissipation against atmospheric resistance, however small. As it comes closer and closer to earth, its speed
a) Decreases progressively
b) Remains constant
c) Becomes non-uniform
d) Increases progressively
Answer: d [Reason:] As the satellite comes closer to the earth, its potential energy decreases. As the sum of kinetic energy and potential energy remains constant, the kinetic energy and the velocity of the satellite increase. But the total energy of the satellite goes on decreasing due to the loss of energy against friction.
4. In inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system. True or false?
Answer: a [Reason:] In inelastic collision, a part of the initial kinetic energy of the system always changes into some other form of energy.
5. In which of the following the momentum and energy of the each body not conserved?
a) Inelastic collision
b) Oblique collision
c) Elastic collision
d) Head on collision
Answer: c [Reason:] In elastic collision, total momentum and total energy of the entire system are conserved and not individual bodies.
6. In an elastic collision of two billiard balls, the total kinetic energy is conserved
b) For a short duration
c) For a long duration but not completely
Answer: b [Reason:] During the short time of collision when the balls are in contact, the kinetic energy of the balls gets converted into the potential energy. In an elastic collision, though the kinetic energy before the collision is equal to the kinetic energy after the collision but kinetic energy is not conserved during the short time of collision.
7. Which of the following is an example for a force which does work on a body but fails to change its kinetic energy?
a) A body pulled through a plain surface
b) A body pulled through a vertical surface
c) A body pulled through a horizontal surface
d) A body at rest
Answer: c [Reason:] When a body is pulled through a rough horizontal surface with constant velocity, work is done by the applied force on the body but kinetic energy of the body remains unchanged.
8. The mechanical energy of a system is always conserved. True or false?
Answer: b [Reason:] The mechanical energy is conserved only when conservative forces are involved and the system should be isolated. Thus the mechanical energy is not always conserved.
9. Two masses of 1g and 4g are moving with equal kinetic energy. The ratio of the magnitudes of their momenta is
Answer: c [Reason:] p = √2mK
For same K, P1/P2 =√(m1/m2 ) = 1/2 = 1:2
10. If a machine is lubricated with oil
a) The mechanical advantage of the machine increases
b) The mechanical efficiency of the machine increases
c) Both its mechanical advantage and efficiency increases
d) Its efficiency increases, but its mechanical advantage decreases
Answer: b [Reason:] When a machine is lubricated with oil, energy wastage against friction decreases. This increases the mechanical efficiency of the machine.
1. When force and displacement are in the same direction, the kinetic energy of the body
c) Remains constant
d) Becomes zero
Answer: a [Reason:] When force and displacement are in the same direction, the kinetic energy of the body increases. The increase in kinetic energy is equal to the work done on the body.
2. The momentum of a body of mass 5kg is 500kgm/s. Find its kinetic energy
a) 2×105 J
b) 2.5×104 J
c) 2.5×105 J
Answer: b [Reason:] Kinetic energy = p2/2m = 5002/(2×5)
Kinetic energy = 2.5×104 J
3. A bullet of mass 20g is found to pass two points 30m apart in a time interval of 4s. Calculate the kinetic energy of the bullet if it moves with constant speed.
Answer: c [Reason:] Speed, v = (Distacne )/Time = 7.5m/s
Kinetic energy = 1/2×0.02×7.52 = 0.5625J
4. Potential energy is also called mutual energy. True or false?
Answer: a [Reason:] Potential energy is also called mutual energy. It is measured by the amount of work that body or system can do in passing from its present position to some standard position, called zero position.
5. The kinetic energy is water is used to run turbines. True or false?
Answer: b [Reason:] The potential energy of water stored to great heights in dams is used to run turbines for generating hydroelectricity.
6. What energy does a stretched bow posses?
a) Kinetic energy
b) Gravitational energy
c) Elastic potential energy
d) Potential energy
Answer: d [Reason:] A stretched bow possesses potential energy. As soon as it is released, it shoots the arrow in the forward direction with a large velocity. The potential energy of the stretched bow gets converted into the kinetic energy.
7. Which of the following is not a conservative force?
a) Elastic force
b) Gravitational force
c) Force of friction
d) Electrostatic force
Answer: c [Reason:] A force is conservative if the work done by the force in moving the particle around any closed path is zero. Therefore, force of fiction is the non conservative force.
8. Calculate the velocity of the bob of a simple pendulum at its mean position if it is able to rise to a vertical height of 10cm. Take g = 9.8m/s2
Answer: d [Reason:] By conservation of energy,
Kinetic energy of the bob at the mean position = Potential energy of the bob at the highest position
That is, 1/2mv2=mgh
v = √2gh = √(2×9.8×0.10) = 1.4m/s
9. How high must the body be lifted to gain an amount of potential energy equal to the kinetic energy it has when moving at a speed of 20m/s? g=9.8m/s2
Answer: b [Reason:] mgh = 1/2mv2 h = v2/2g = 20.2m
10. A ball is thrown vertically upwards with a velocity of 20m/s. At what height, will its kinetic energy be half its original value?
Answer: a [Reason:] Work done against gravitation = Change in kinetic energy
mgh = 1/2 mv2-1/2×1/2 mv2 h = v2/4g= 10.20m
1. Which of the following is the characteristic of a black body?
a) A perfect absorber but an imperfect radiator
b) A perfect radiator but an imperfect absorber
c) A perfect radiator and a perfect absorber
d) A perfect conductor
Answer: c [Reason:] When the radiations are made to pass through a black body, it undergoes multiple reflections and is completely absorbed. When it is placed in a temperature bath of fixed temperature, the heat radiations will come out. Thus a black body is a perfect absorber and a perfect reflector.
2. The energy distribution is not uniform for any given temperature in a perfect black body. True or false?
Answer: a [Reason:] At different temperatures, when a perfect black body is allowed to emit radiations, then the distribution of energy for different wavelengths at various temperatures is not uniform.
3. Rayleigh-Jean’s law hold good for which of the following?
a) Shorter wavelength
b) Longer wavelength
c) High temperature
d) High energy
Answer: b [Reason:] According to this law, the energy distribution is directly proportional to the absolute temperature and is inversely proportional to the fourth power of the wavelength. Therefore longer the wavelength, greater is the energy distribution.
4. Wien’s displacement law hols good only for shorter wavelength. True or false?
Answer: b [Reason:] This law states that, the product of the wavelength, corresponding to maximum energy and the absolute temperature, is constant. If ʎ is less, then 1/ʎ will be great. Therefore e(hc/ʎKT) will be great.
5. Which of the following does not affect the photon?
a) Magnetic or electric field
b) Light waves
Answer: a [Reason:] Photons have no charge. They can interact with charged particles but not with themselves. This is why photons are neutral and not affected by magnetic or electric fields.
6. What is Compton shift?
a) Shift in frequency
b) Shift in charges
c) Shift in radiation
d) Shift in wavelength
Answer: d [Reason:] When a photon collides with an electron at rest, the photon gives its energy to the electron. Therefore the scattered photon will have higher wavelength compared to the wavelength of incident photon. This shift in wavelength is called Compton shift.
7. Compton shift depends on which of the following?
a) Incident radiation
b) Nature of scattering substance
c) Angle of scattering
d) Amplitude of frequency
Answer: c [Reason:] From the theory of Compton effect it is deducted that change in wavelength
Δʎ = h/mc (1-cosɵ). This equation shows that, the change in wavelength is independent of the incident radiation as well as the nature of scattering substance. The shift depends only on the angle of scattering.
8. Which of the following is called as non-mechanical waves?
a) Magnetic waves
b) Electromagnetic waves
c) Electrical waves
d) Matter waves
Answer: b [Reason:] The waves which travel in the form of oscillating electric and magnetic waves are called electromagnetic waves. Such waves do not require any material for their propagation and are called non-mechanical waves.
9. Which of the following is associated with electron microscope?
a) Matter waves
b) Electrical waves
c) Magnetic waves
d) Electromagnetic waves
Answer: a [Reason:] The waves associated with microscopic particles when they are in motion are called matter waves. Electron microscope makes use of the matter waves associated with fast moving electrons.
10. A radio station broadcasts its programme at 219.3 metre wavelength. Determine the frequency of radio waves if velocity of radio waves is 3×108 m/s.
a) 7.31×10-7 Hz
b) 1.954×10-6 Hz
c) 1.368×106 Hz
d) 6.579×1010 Hz
Answer: c [Reason:] ʎ = velocity/frequency
Frequency = velocity/ʎ
Therefore, frequency = 1.368×106 Hz.
11. Calculate the de-Broglie wavelength of an electron which has been accelerated from rest on application of potential of 400volts.
a) 0.1653 Å
b) 0.5125 Å
c) 0.6135 Å
d) 0.2514 Å
Answer: c [Reason:] de-Broglie wavelength = h/√(2×m×e×V)
De-Broglie wavelength = (6.625×10-14)/√(2×9.11×10-31×1.6×10-17×400)
Wavelength = 0.6135 Å
1. The earth moving around the sun in a circular orbit is acted upon by a force and hence work must be done on the earth by the force. True or false?
Answer: b [Reason:] The gravitational force is a conservative force. So the work done by the gravitational force over every complete orbit of the earth is zero.
2. A force can do no work on a body, yet the body can move under accelerated motion. True or false?
Answer: a [Reason:] When the force is perpendicular to the direction of motion, the force can do no work on a body even if it is under accelerated motion. The moon revolves around the earth under the centripetal force of attraction of the earth, but earth does no work on the moon.
3. What sort of energy does a flying bird posses?
a) Potential energy
b) Kinetic energy
c) Elastic energy
d) Both potential and kinetic energy
Answer: d [Reason:] A flying bird possesses both kinetic and potential energies because it is at a certain height above the ground and moving with a certain velocity.
4. When a spring is compressed or stretched, the potential energy of the spring
b) Stays constant
d) Becomes zero
Answer: c [Reason:] The potential energy of a spring increases when it is compressed or stretched because work is done on it when it is compressed or stretched.
5. The water at the foot of the fall will be at a different temperature from that at the top. True or false?
Answer: a [Reason:] When water falls from a height, its potential energy is converted into kinetic energy and its velocity is maximum at the foot of the fall. The velocity is suddenly reduced to zero, and hence its kinetic energy gets converted into heat energy raising its temperature.
6. When the momentum of a body is doubled, its kinetic energy
a) Remains the same
b) Drops to zero
c) Becomes four times its initial kinetic energy
d) Becomes ten times its kinetic energy
Answer: a [Reason:] K = 1/2 mv2 = (mv)2/2 m = p2/2 m
K α p2 When the momentum of a body is doubled, its kinetic energy becomes four times the initial kinetic energy.
7. When the velocity of an aeroplane is doubled, the momentum
a) Remains unchanged
b) Is conserved
c) Becomes zero
d) Increases uniformly
Answer: b [Reason:] If velocity of the aeroplane is doubled, its momentum is also doubled. However, combined momentum of air and aeroplane is conserved. As the momentum of aeroplane increases, the momentum of air also increases by an equal amount in the opposite direction.
8. What happens to the potential energy when one proton and one electron are brought close together?
a) The potential energy gets increased
b) The potential energy gets converted into kinetic energy
c) The potential energy gets remains the same
d) The potential energy gets decreased
Answer: d [Reason:] The potential energy gets decreased when a proton and an electron are brought close because the work is done by the force of attraction between them.
9. In a thermal power station, coal is used for the generation of electricity. How energy changes from one form to another before it is transformed into electrical energy?
a) Heat energyMechanical energyElectrical energy
b) Heat energyElectrical energyMechanical energy
c) Mechanical energyHeat energyElectrical energy
d) Electrical energyHeat energyMechanical energy
Answer: a [Reason:] The heat energy produced due to combustion of coal converts water into steam. The heat energy of steam is converted into mechanical energy when it turns blades of a turbine. The mechanical energy so obtained is converted into electrical energy by the generators.
10. A metal ball rebounds better than rubber ball. True or false?
Answer: a [Reason:] When a rubber ball hits a massive object, it is distorted. A large amount of heat is generated in the ball by the rubbing of the rubber molecules against each other. This effect is essentially absent in a hard material. So, a metal ball would lose less energy upon collision than would a rubber ball.