一、选择题1.下列叙述能用质量守恒定律解释的是()。A.水结成冰前后质量保持不变B.镁带燃烧所得产物的质量大于镁带的质量C.50 g水和50 g蔗糖混合后总质量为100 gD.胆矾研磨后质量保持不变2.碳酸很不稳定,常温下就会分解生成二氧化碳和水,这一事实说明()。A.碳酸是二氧化碳和水组成的纯净物 First, the multiple-choice questions 1. The following statement can be explained by the law of conservation of mass (). A. water before and after the ice into the same quality remains unchanged B. The quality of the magnesium products with the combustion of magnesium is greater than the quality of the magnesium belt C.50 g water and 50 g of sucrose mixed total mass of 100 gD. 2.Carbonate is very unstable, at room temperature will be decomposed into carbon dioxide and water, a fact that (). A. Carbonate is a pure substance consisting of carbon dioxide and water