For each of the compounds, writ
19. (NH4)2S
Formula

chemical properties are the characteristic of matter which can only be observed by changing the chemical identity of a sample like flammability reactivity and toxicity.

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