Help please I don’t know how to do thid

Which is a chemical property of iron? a. it forms iron oxide (rust) when exposed to moisture and air. b. it is a gray–black metal that is hard to the touch. c. it has a melting point of 2795°f (1536°c). d. it is a good conductor of heat

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

What is the molar mass of the anhydrous compound? answer using four significant figures. 36.02 g/mol 120.15 g/mol 156.12 g/mol