Which best describes a compound such as sodium chloride? a pure substance that can be separated into different elements by physical means
a mixture of two common substances that can be separated by chemical means
a mixture of two common elements that can be separated by physical means
a pure substance that can be separated into different elements by chemical means

i think it is the last option a pure substance that can be separated into different elements by chemical means

Explanation:

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

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.