When a helium balloon rises in the air, it expands. if the volume of the balloon doubles, what happens to the density of the helium inside it
a. the density decreases by half.
b. the density doubles.
c. the density stays the same.
d. the density triples

Below, the levels of organization in a multicellular organism are shown from least to most complex. which level of organization can be described as several different types of tissues working together to perform a common task?

Draw the farm's ppf for corn and beef. draw a point that shows an inefficient combination of corn and beef. label ita. draw a point that shows an unattainable combination of corn and beef. label itb. draw a point that shows an efficient combination of corn and beef. label itc.

Name three things that show evidence of evolution. write one sentence for each, explaining why it demonstrates evidence. (9 points)