I need HELP! Question 1: Which condition helps determine the quality of lake water?

A) the amount of dissolved calcium carbonate

B) the amount of nitrogen

C) the amount of potassium

D) the amount of dissolved oxygen

Fugu, also known as puffer fish, is a sushi delicacy that can also be lethal. puffer fish contain a powerful toxin that can kill an adult a few hours after ingestion. sushi chefs who prepare fugu must be specially trained because any contamination of the toxin-free areas of the fish can be deadly. recently this toxin has been put to good use, as scientists have discovered that a purified form of it can treat severe pain in cancer patients. this recent scientific discovery would fall under which area of chemistry? applied biochemistry pure organic chemistry pure physical chemistry applied inorganic chemistry

You have 125g of a certain seasoning and are told that it contains 76.0 g of salt what is the percentage of salt by mass in this seasoning

Compare and contrast physical changes with chemical changes.