The half-life of cobalt 60 is 5.3 years. What fraction of a sample remains after 21.2 years?

A.

one half

B.

one quarter

C.

one eighth

D.

one sixteenth

The main function of this hormone is to stimulate the development and growth of the male genital tract. What is this hormone?

The branch of chemistry that involves the study of substances and processes occurring in living things is called?

Which of the following components of the immune system form memory cells after you receive a vaccine? Skin and saliva Monocytes and macrophages Neutrophils and histamines B and T cells

Why are mosquitos classified as Arthropods?

The mechanical breakdown of rocks by the action of other rocks and sand particles is called

The overall population of a species decreased. What could have occurred to make this happen? The immigration rate increased, while the death rate decreased. The birth rate decreased, while the death rate increased.

Which of the following terrestrial biomes cannot be found in the United States? A: temperature deciduous forest B: tundra C: desert D: grassland/prairie

Which of these food sources does the bald eagle not feed on? plants fish carrion mammals

what will happen to a base isolated building when seismic wave strike the building during an earthquake

The shape and size of a birds beak would mostly be affected by what environmental limiting factor