A certain element has a half-life of 1,000 years. How much of a sample of this element remains after 2,000 years?

A quarter of the sample.

Explanation:

Let the quantity at the beginning be T. If the element has a half-life of 1,000 years, it means that after 1000 years, T/2 (which represents half the initial quantity available) would have decayed, remaining T/2.

After another 1000 years (making 2000 years), T/4 (which represents have of the quantity left after the first 1000 years) would have decayed, remaining T/4.

This means that only a quarter of T would be left after 2000 years.

the transfer for conduction is the heat transfering from the liquid to the spoon

the transfer for convection is the heat rising from the liquid to the air

the transfer for radiation is the heat going through the sides of the cup and to the air

at least that is what i would do

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.