Determine the number of moles of phosphine gas that is formed when hydrogen gas reacts with phosphorus (at STP) to form 15.3 g of phosphine (PH3). (molar masses: P = 30.97g/mol, H = 1.01g/mol)

What is the formula that this ionic compounds could form sr2+p3-o2-

Several kinds of bears are found on earth. most bears are brown or black, but one type of bear, the polar bear, is white. what process led to this difference in fur color? explain your answer.

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange