Calculate the mass of sodium nitrate needed to make 100 ml of 0.1 mol/l concentration.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the major pests we deal with are insects, weeds and fungal diseases. a pesticide is a product, whether organic or chemical, used to kill the target pest. there are other techniques gardeners should use that can prevent the severe infestations that make the use of pesticides necessary