what is the correct answer for these mcqs?

How many bits to store hexadecimal word AF?
what is unavailable energy in a system called?
permanent hardness of water is due to?
Human beings main nitrogenous waste is? ammonia or urea?
What control rods used in nuclear reactors? cadmium or graphite?
what is pre-released software's designation? beta, alpha or omega?
which country lies on the equator somethng like that?
vessel that gives blood to liver is?
what isnt included in earth's envrionment? litho or stratosphere?
and what is anthracite?

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