Help.. How long will it take three quarters of a sample of a radioactive
element to decay if its half-life is 4 days?
a. 2 days
b. 3 days
c. 4 days
d. 8 days

Amarine ecologist has constructed the conceptual model shown in the diagram. what predictions can be made from using this model? where the tertiary consumers get their energy how often primary producers are able to reproduce when bacteria and fungi initiate the process of decomposition whether other secondary consumers are present

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

As scientist had investigated evolution from a variety fields they have found