The volume of a pond being studied for the effects of acid rain is 35 kiloliters (kL). There are 1,000 liters (L) in 1 kL and 1 x 10^6 microliters (mL) in 1 L. Multply 35 by 1000/1x10^6
35 kL (1000 liters/ 1 kL) (1 x 10^6 mL/ 1 L) = 3.5 x 10^9 microliters