Radiocarbon is produced in the atmosphere as a result of

A) collision between fast neutrons and nitrogen nuclei present in the atmosphere
B) action of ultraviolet light from the sun on atmospheric oxygen
C) action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere
D) lightning discharge in atmosphere

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Stars appears to move from east to west because

A) all stars move from east to west
B) the earth rotates from west to east
C) the earth rotates from east to west
D) the background of the stars moves from west to east

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Siphon will fail to work if

A) the densities of the liquid in the two vessels are equal
B) the level of the liquid in the two vessels are at the same height
C) both its limbs are of unequal length
D) the temperature of the liquids in the two vessels are the same

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Out of the following pairs, choose the pair in which the physical quantities do not have identical dimension?

A) Pressure and Young modules
B) Planck constant and Angular momentum
C) Impulse and moment of force
D) Force and rate of change of linear momentum

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Rectifiers are used to convert

A) Direct current to Alternating current
B) Alternating current to Direct current
C) high voltage to low voltage
D) low voltage to high voltage

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