The ratio of reactant in grams would be influenced by the reaction equation and the molar mass of the elements. But the ratio of a reactant needed in grams would be same for a reaction.
If 2 grams of element X combine with 4 grams of element Y to form compound XY, it means the ratio of reactant in grams<span> would be 2:4 or 1:2
The number of element X needed for 28grams of element Y would be:
1/2 * 28grams = 14 grams.</span>
4.7e^6 is how I would write it. You simply count in from the right side where the decimal is until you reach the point just before the 4.
Your question is incomplete. However, I found a similar problem fromanother website as shown in the attached picture.
To solve this problem, you must know that at STP, the volume for any gas is 22.4 L/mol. So,
Moles O₂: 156.8 mL * 1 L/1000 mL* 1 mol/22.4 L = 0.007 moles
Mass calcium: 0.007 mol O₂ * 2 mol Ca/1 mol O₂ * 40 g/mol Ca =
<em> 0.56 g Ca</em>