At STP, 1.00 g of calcium is placed into an acidic solution, and 407 mL of hydrogen gas is collected. What is the ratio of moles of calcium consumed to moles of hydrogen produced?

a)1.37:1.00
b)1.00:1.64
c)0.928:1.00
d) 0.500:1.00

Is the answer A, if so, can you explain the process.

Your question is about chemistry, not calculus.

Convert the volume of gas released (at STP) to moles. That would be 0.407/22.4 = 0.0182 moles. 1 g of Ca is 1/40 = 0.0250 moles. Get the ratio from those numbers and round it off. It will be one of the 4 choices