Asubstance that enters earth's cycles and does harm to living things is
a. a pollutant.
b. hydrogen.
c. freshwater.
d. oxygen.

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

Which is not true about balanced forces?

Aquantity of gas has a volume of 18 m3 and an absolute temperature of 225 k. when the temperature of the gas is raised to 380 k, what is the new volume of the gas? (assume that there’s no change in pressure.)