阅读短文，选择最佳答案。

    Hello, I am John. Look, this is a picture 1 my room. I have a nice bed in the middle of my room. There is a big table 2 the closet and the bed. Many clothes are3 the closet. A white air-conditioner is 4 the wall beside the window. There is a computer on the table. I often write e-mails with it.

   Do you like my room? What's your room 5? Can you tell me, please?

硝化甘油为一种烈性炸药，应用于矿山、国防等多方面。它的化学式为C₃H₅N₃O₉，每个分子中共有____个原子，它的相对分子质量是____，氢元素和氮元素的质量比为____。