Anybody know the answer?​

Which type of reaction always has an element and a compound as reactants

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

The molar mass of nickel(ni) is 58.7 g/mol. how many moles are in an 88 gram sample of nickel?