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Page-18 |
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Physical Science |
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| 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 | ||
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| 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. |
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| 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 | ||
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| 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 | ||
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| 254)A common flurescent tube contains | |||
| argon at low pressure | sodium vapour | ||
| mercuric oxide and neon | mercury vapour at low pressure | ||
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| 255)In which of the following industries is mica used as a raw meterial? | |||
| iron and steel | toys | ||
| electrical | glass and pottery | ||
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| 256)The effective radius of an atom is | |||
| 10-8m | 10-10m | ||
| 10-12m | 10-15m | ||
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| 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 | ||
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| 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 | ||
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| 259)The nucleus of an atom contains | |||
| protons and electrons | protons and neutrons | ||
| only neutrons | neutrons and electrons | ||
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| 260)Phenomenon of spontaneous disintegration of heavy nucleus is termed as | |||
| fusion | fission | ||
| radioactivity | implosion | ||
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| 261)Radioactivity has applications in | |||
| Medicine | Industry | ||
| agriculture | all of these | ||
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| 262)Which of the following waved/ rays are produced by nuclear changes in the atom? | |||
| infra red | X-rays | ||
| γ-rays | lighe waves | ||
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| 263)Gamma raditions are used for | |||
| controlling pests | cancer therapy | ||
| sterilization foodstuff | all of these | ||
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| 264)Radioisotopes are | |||
| isotopes used in radio sets | some nuclei which emit radiowaves | ||
| isotopes that are radioactive | none of these | ||
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| 265)Radiocarbon dating technique is used to estinmate the age of | |||
| fossils | rock | ||
| soil | building | ||
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