Matter is niether created nor destroyed in any chemical change. is this a theory or a law?

Agas diffuses 1/7 times faster than hydrogen gas (h2). what is the molar mass of the gas? 100.10 g/mol 98.78 g/mol 86.68 g/mol 79.98 g/mol

6what is the importance of water on earth? a) it keeps the top layer of the geosphere cool b) it allows life to exist c) it provides ice at the poles d) it creates earth's blue color from space

What is the correct equation for cellular respiration?