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Questions from RRB, NTPC, Group D and JE past papers. Tap an option to check it instantly — every question shows the correct answer, and most carry the explanation the paper gave.
Correct option: B — Half the height of the person
The minimum height of a plane mirror to see the full size image of a person is equal to the half the height of the person.
Correct option: C — Total internal reflection of light
An endoscopic process is based on the principle of total internal reflection of light.
Correct option: B — Uncontrolled fusion reaction
Thermonuclear fusion, or hydrogen bombs explode with enormous power using uncontrolled self-sustaining chain fusion reactions. Deuterium and tritium, under extremely high temperatures, form helium providing the energy. D + T o 4He + n In principle, a mixture of D, T and 6Li heated to very high temperature and confined to a high density will start a chain fusion reaction, liberating an enormous amount of energy.
Correct option: D — Does not form an explosive mixture with air
Hydrogen combines with oxygen with explosive force in the presence of a spark.Helium is an inert gas that will not burn or explode, so is much safer to use in balloons instead of hydrogen.
Correct option: B — Carbon, Hydrogen, Nitrogen
Carbon, hydrogen and nitrogen were primarily responsible for the origin of life on the earth. 39 (a) Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids.
Correct option: A — Joule
Correct option: D — Ohm-metre
Correct option: C — Watt
Correct option: C — Newton
Correct option: A — Distance
Page 1 of this set has 10 questions on it.
