How can you tell if a sample contains baking soda and cornstarch or baking powder

You could mix it with some vinegar, if it has cornstarch or baking soda in it will bubble, I'm not sure how to tell with baking powder... I'm not sure if it would have a reaction or not.

Hope this helps.

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