Physical Science

251)Air is completely removed from an electric bulb to prevent
bursting of the bulb oxidation of tungsten filament
loss of light due to absorption none of these
Answer :

252)Assertio: When an electric bulb is switched on, the resistance of its tungsten filament increases.
Reason : The resistance of pure metals increases on heating.
Both A and R are correct and R explains A Both A and R are correct but R does not explains A
A is correct, R is wrong Both A and R are wrong
Answer :

253)When an electric bulb breaks, there is a mild bang due to
chemical reaction between the enclosed gases the air rushing in to fill the evacuated space
the compressed gases rushing our suddenly some other reason
Answer :

254)A common flurescent tube contains
argon at low pressure sodium vapour
mercuric oxide and neon mercury vapour at low pressure
Answer :

255)In which of the following industries is mica used as a raw meterial?
iron and steel toys
electrical glass and pottery
Answer :

256)The effective radius of an atom is
10-8m 10-10m
10-12m 10-15m
Answer :

257)Which of the following rays are produced when very high energy electrons are stopped suddenly at a metal target?
Α - ray β - ray
γ-ray X-ray
Answer :

258)The force between two protons (positively charged particles) is
always attractive always repulsive
always zero attractive or repulsive depending on the distance between them
Answer :

259)The nucleus of an atom contains
protons and electrons protons and neutrons
only neutrons neutrons and electrons
Answer :

260)Phenomenon of spontaneous disintegration of heavy nucleus is termed as
fusion fission
radioactivity implosion
Answer :

261)Radioactivity has applications in
Medicine Industry
agriculture all of these
Answer :

262)Which of the following waved/ rays are produced by nuclear changes in the atom?
infra red X-rays
γ-rays lighe waves
Answer :

263)Gamma raditions are used for
controlling pests cancer therapy
sterilization foodstuff all of these
Answer :

264)Radioisotopes are
isotopes used in radio sets some nuclei which emit radiowaves
isotopes that are radioactive none of these
Answer :

265)Radiocarbon dating technique is used to estinmate the age of
fossils rock
soil building
Answer :

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