题干

 化学与生产、生活有着密切联系.

(1)玻璃的主要成分是二氧化硅,盛装NaOH的试剂瓶瓶塞是橡胶塞.如果是玻璃塞,则会与NaOH反应而使瓶颈与瓶塞粘连无法打开,请用化学反应方程式表示其原理____ .

(2)中秋节是中华民族的传统节日,天南地北的华人都有赏月吃朋饼的习俗.而在制月饼时会在面粉中加入发酵粉:小苏打,在焙制月饼时需高温加热.而小苏打热稳定性差,试写出其受热分解的化学方程式____ .

(3)建设社会主义新农村的任务之一是改变农村的燃料,改善农村生活环境,提高生活质量、国家鼓励和支持建造沼气池.请写出沼气燃烧的化学方程式____ .

(4)已知某物质的化学式为RCl3.试写出R硫酸盐的化学式____ .

上一题 下一题 0.0难度 选择题 更新时间:2015-09-23 06:19:56

答案(点此获取答案解析)

2NaOH+SiO2\u2550Na2SiO3+H2O,2NaHCO3=\u25b3Na2CO3

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    It snowed again. My seventh Christmas was round the corner. I dreamed of getting the present from Father Christmas until my elder sister dropped the bomb, “There is no Father Christmas.”
I ran to my grandmother’s house, for she always told the truth. Grandma was at home. I told 1 everything. "No Father Christmas?" she was a little 2. “Don't believe it. Put on your coat, and let's go.”
   “Go? Where, Grandma?” I asked.
   “Kerby's Store.”
    As we walked through its doors, Grandma handed me ten dollars and said, "Take the 3 and buy something for someone who needs it. I'll wait for in the car.”Then she turned and walked out of the Kerby's.
    For a few seconds I just stood there, holding the money, wondering 4 to buy, and who to buy it for.
    I thought of 5 I knew: my family, my friends, my neighbors … I suddenly thought of Bobbie Decker, a 6 with bad and messy hair. He sat right behind me 7 Mrs. Pollack's class.
    Bobbie 8 went to any party during the winter. His mother always wrote a note, telling the teacher that he had a cough, 9 we all knew that he didn't have a cough, and he didn't have a coat. I decided to buy Bobbie a red warm coat 10 he would like.
    That evening, Grandma helped me wrap the coat in Christmas paper and ribbons, and 11 “To Bobbie, From Father Christmas” on it. Grandma told me Father Christmas never let people know that he 12 them. Then she drove me over to Bobbie's house, telling that I was helping Father Christmas 13 the presents.
    Grandma parked the car along the street, and we hid behind the trees near Bobbie's house. Then Grandma said to me, “All right, Father Christmas, get going.”
    I took a deep breath, rushed to his front door, put the present down. 14 the door, rang the doorbell and flew back to the safety of the 15 and Grandma. We waited breathlessly in the dark for the front door to open. Finally it did, and there stood Bobbie.
That night, I realized that Father Christmas was alive and well, and we were on his team.