Your reaction will produce 0.624 g of hydrogen gas.
Start by writing the balanced chemical equation for this reaction
Notice that you have a
Determine how many moles of calcium reacted by using its molar mass
Because water is in excess, i.e. it will not act as a limiting reagent, you can assume that all of the calcium will react. This means that your reaction will produce
Now use hydrogen gas' molar mass to see how many grams you'd get
Rounded to three sig figs, the answer will be