General Science Page-3

21) Which one of the following does a TV remote control unit use to operate a TV set?
(A) Light waves
(B) Sound waves
(C) Microwaves
(D) Radio waves

22) A small pouch containing silica gel is often found in bottles of medicine in tablet or powder form because silica gel
(A) Kills bacteria
(B) Kills germs and spores
(C) Absorbs moisture
(D) Absorbs all gases present inside the bottle

23) Fluorescent tubes are fitted with a choke. The choke coil:
(A) Steps up the line voltage
(B) Steps down the line voltage
(C) Reduces current in the circuit
(D) Chokes low frequency currents

24) For reproducing sound, a CD (Compact Disc) audio player uses a:
(A) Quartz crystal
(B) Titanium needle
(C) Laser beam
(D) Barium titanate ceramic

25) When a CD (compact disc used in audio and video systems) is seen in sunlight rainbow like colours are seen. This can be explained on the basis of the phenomenon of:
(A) Reflection and diffraction
(B) Reflection and transmission
(C) Diffraction and transmission
(D) refraction, diffraction and transmission

26) If a U-238 nucleus splits into two identical parts, the two nuclei so produced will be:
(A) Radioactive
(B) Stable
(C) Isotopes
(D) Isobars

27) Which of the following types radiations is absorbed by the upper layer of the atmosphere?
(A) Radio-waves
(B) Infrared
(C) Visible
(D) Ultraviolet

28) After long period of use, a gray spot develops on the inside of a bulb. This is because:
(A) The tungsten filament evaporates and collects there
(B) The heat of the bulb scorches the glass at the top
(C) Dust inside the bulb condenses on the top
(D) Glass undergoes a change due to the heat

29) Approximately, how many times each day do our heart valves open and close manually?
(A) 10,000
(B) 1,00,000
(C) 1,50,000
(D) 2,00,000

30) A nuclear reactor harnesses nuclear energy by:
(A) Nuclear fusion
(B) Spontaneous fission
(C) Uncontrolled chain reaction
(D) Controlled chain reaction

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