391. Diamond is a very expensive ornament. It is composed of a single element ___________?
A. Carbon
B. Gold
C. Silver
D. Platinum
E. None of these

392. Which of the following layers make radio transmission possible?
A. Troposphere
B. Ionosphere
C. Mesosphere
D. Stratosphere
E. None of these

393. Which of the following explains the reason why there is no total eclipse of the sun?
A. Size of the earth in relation to that of moon
B. Orbit of moon around earth
C. Direction of rotation of earth around sun
D. Area of the sun covered by the moon
E. None of these

394. Television signals are converted into light signals by___________?
A. Optical fiber
B. Transistor
C. Decoder
D. Photo diode
E. None of these

395. Where do most of Asteroids lie?
A. In asteroid belt between the orbits of Mars and Jupiter
B. In asteroid belt between the orbits of Mars and Venus
C. In asteroid belt between the orbits of Jupiter and Venus
D. Everywhere in the sky
E. None of these

396. The number of spark plugs needed in a diesel engine is__________?
A. 2
B. 3
C. 0
D. 4
E. None of these

397. The half life of a radioactive element is 8-days. How long it take to reduce it from 10 mg to 5 mg?
A. 4 days
B. 12 days
C. 16 days
D. 8 days
E. None of these

398. The term ‘Blue Shift’ is used to indicate?
A. Doppler effect in which an object appears bluer when it is moving towards the observer or observer is moving towards the object.
B. Turning a star from white to blue
C. In future sun would become blue
D. Black hole was blue at its start
E. None of these

399. Kilowatt-hour is a unit of____________?
A. Power
B. Electric Current
C. Energy
D. Time
E. None of these

400. Fuel used in a Fast Breeder Reactor is _____________?
A. Uranium Oxide
B. Uranium Plutonium carbide
C. Uranium Plutonium Oxide
D. Uranium thorium Oxide
E. None of these