A fresh set of 20 random questions is generated every time you open this page and every time you refresh it.For each of the following multiple choice questions, choose the most appropriate answer :
1. A radioactive substance decays to 1/16 of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is
A. 2.5
B. 5
C. 10
D. 20
2. Satisfactory explanation oi the phenomenon of photo electric effect is based on
A. Planck's quantum theory
B. Einstein's theory of relativity
C. Huygen's wave theory
D. Newton's corpuscular theory
3. When analyzed, most complicated machines are found to consist of a combination of various simple machines. Which machine below is NOT a simple machine ?
A. lever
B. electric motor
C. inclined plane
D. pulley
4. When a guitar string is surrounded with a 440 Hz tuning fork, a beat frequency of 5 Hz is heard. It the experiment is repeated with a tuning fork of 437 Hz, the beat frequency is 8 Hz. The string frequency is
A. 445 Hz
B. 435 Hz
C. 429 Hz
D. 448 Hz
5. An earthquake generates both transverse 8 and longitudinal P sound waves in the earth. The speed of 8 waves is about 4.5 km/s and that of P waves is about 8.0 km/s. A seismograph records P and 8 waves from an earthquake. The first P wave arrives 4.0 min before the first 8 wave. The epicenter of the earthquake is located at a distance of about
A. 25 km
B. 8 250 km
C. 2500 km
D. 5000 km
6. The velocity with which a projectile must be fired so that it escapes earth's gravitation does not depend on
A. Mass of the earth
B. Mass of the projectile
C. Radius of the projectile's orbit
D. Gravitational constant
7. A capacitor of capacity C has charge Q and stored energy is W. If the charge is increased to 2Q, the stored energy will be
A. W/4
B. 4W
C. W/2
D. 2W
8. If a planet of given density were: made larger keeping its density unchanged its force of attraction for an object on its surface would increase because of increased mass of the planet but would decrease because of larger separation between the centre of the planet and its surface. Which effect would dominate?
A. Increase in mass
B. Increase in radius
C. Both affect the attraction equally
D. None of the above
9. To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
A. A conductor
B. A p-type semiconductor
C. An n-type semiconductor
D. An insulator
10. Which of the following logic gates is an universal gate ?
A. NAND
B. AND
C. OR
D. NOT
11. A gas mixture consists of 2 moles of oxygen and 4 moles of argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is
A. 11RT
B. 9RT
C. 15RT
D. 4RT
12. A child is swinging a swing. Minimum and maximum heights of swing from earth’s surface are 0.75 m and 2m respectively. The maximum velocity of this swing is?
A. 5 m/s
B. 10 m/s
C. 15 m/s
D. 20 m/s
13. A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass m is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period
A. increases contmuously
B. remams unaltered
C. decreases continuously
D. decreases initially and increases again
14. Which of the statements below is courect ?
A. The angle of bank for a road is obtained from a consideration of the centripetal force required
B. There is no tendency for the vehicle to skid if a road is banked for the speed at which the vehicle is moving
C. C. The resultant force action on the vehicle will be that which maintains it in the circular path
D. All of the above statements are correct
15. If the distance between two similar magnetic poles held one cm apart be doubled, then the force of interaction between them will be
A. Halved
B. Doubled
C. Unchanged
D. One quarter ot the original value
16. With what minimum acceleration can a firemen slide down a rope while breaking strength of the rope is 2/3 his weight
A. g/3
B. 2g/3
C. zero
D. g
17. Which statement is false ?
A. The gas pressure per unit volume is 2/3 of the mean kinetic energy
B. In a perfect gas, there is no force of attraction among the molecules
C. The RMS velocity of the gas molecules is proportional to its absolute temperature
D. The RMS velocity of the gas molecules is inversely proportional to the square root of the molecular weight
18. You are standing 1000 m from the point where a steel block strlkes the sldewalk. How long will lt take the sound to reach your ears if the speed of sound in air at 0° C is about 333 m/sec. ?
A. 3 seconds
B. 2 seconds
C. 1 second
D. 5 seconds
19. A body of mass 0.5 kg is whirled in a vertical circle at an angular frequency of 10 rad/s. lf the radius of the circle is 0.5 m, what is the tension in the string when the body is at the top of the circle ? Take g = l0 m/s2
A. 40N
B. 30N
C. 20N
D. 10N
20. When a beta-particle is emitted from a nucleus, the neutron-proton ratio
A. is increased
B. is decreased
C. remains the same
D. first decreases then increases
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