What contributes to air pollution
a. mowing the lawn
b. watering the lawn
c. burning leaves and brush
d. sprinkling fertilizer around plants

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?