What mass of calcium is needed to produce g of hydrogen gas?

To determine the mass of calcium needed to produce a specific mass of hydrogen gas, you first need to know the balanced chemical reaction involved. For instance, the reaction between calcium and water produces hydrogen gas: Ca + 2H₂O → Ca(OH)₂ + H₂. Using stoichiometry, you can calculate the moles of hydrogen produced and then convert that to moles of calcium required, finally using the molar mass of calcium to find the mass needed. Please provide the specific mass of hydrogen gas you are interested in for a precise calculation.