At what radius does the probability density of an electron in the H atom fall to 50 per cent of its maximum value?

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

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )