Please help me
what are six common air pollutants

In 2009, roughly of people age 12 or older who did not drink alcohol were current users of illegal drugs. a. 4% b. 10% c. 13% d. 20%

Ineed an answer for this one (number 8)

Which of these is a disadvantage of hydrogen fuel cells? a. engines that use hydrogen fuel are more efficient than gasoline-powered engines. b. the only emission produced by hydrogen fuel cells is water. c. hydrogen fuel is continually available and useful for heating. d. hydrogen fuel is often purified in a process that emits lots of greenhouse gases.