题干

水能灭火,也能生火,李老师给同学们表演了“水能生火”的魔术(如图):他将包有过氧化氢(Na2O2)粉末的脱脂棉放在石棉网上,向脱脂棉上滴了几滴水,脱脂棉立即燃烧起来,查阅资料知道:过氧化钠与水反应生成的产物只有两种,都是初中化学常见的物质,根据所学化学知识回答:

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Bobby was sitting out in his back yard in the snow. There were a few holes in his shoes. He thought hard, but he could not come up with an idea for his mother's Christmas gift.
Ever since his father had died three years ago, his mother worked nights at the hospital, but the small money she made could hardly be enough for their needs.
Although the family lacked in money and material things, they got more love in the family. The children ran the family when their mother was absent. All three of Bobby's sisters had already made beautiful gifts for their mother.
It was Christmas Eve already, and he had nothing. Bobby started to walk down to the street. He walked from shop to shop. Everything seemed so beautiful and so far away. It was getting dark. Suddenly he found a shiny dime (一角硬币) on the ground. Never has anyone felt so wealthy as Bobby did at the moment. It was enough to buy a rose with one dime.
He went inside a flower shop. When the owner asked if he could help him, Bobby took out the dime and asked if he could buy one flower. The shop owner looked at Bobby, then said, "You just wait here and I’ll see what I can do for you."
The shop owner returned holding a dozen of red roses in his hand. Bobby's heart sank (下沉) as the owner put them gently into a long white box. "That will be a dime, young man," said the shop owner, reaching out his hand for the dime. Slowly, Bobby moved his hand to give the man his dime.
Then the shopkeeper's wife appeared. "Where are the red roses?"
The shop owner said, "A strange thing happened to me this morning. I thought I heard a voice telling me to leave a dozen of my best roses for a special gift. When I saw that little boy tonight, I knew who that voice was."