Stuart measures 10 grams of water into a pan and freezes it a day later he takes the out the freezer and is surprised that it is larger than before he froze it. what is the mass of the ice

The mass of the ice will still be 10 grams, as the matter in the water remains the same when it freezes. However, the volume of the ice will be larger than the water, as water expands when it freezes into ice.