高温下丁烷完全裂化生成四种气体，将混合气体用溴水处理后，剩余气体的平均分子质量为21.6，则原四种混合气体的平均分子质量是
A．21.6
B．27.6
C．29
D．36.4
答案：C
题目分析：丁烷裂化的方程式是C4H10
C2H4+C2H6、C4H10CH4+C3H6。能被溴水吸收的是烯烃，则剩余气体是甲烷和乙烷，平均相对分子质量是21.6，则根据十字交叉法可得出甲烷和乙烷的物质的量之比是3:2。由方程可得，乙烷和乙烯的物质的量相等、甲烷和丙烯的物质的量相等，所以混合气体的平均相对分子质量是
，答案选C。
点评：该题是中等难度计算题的考查，试题紧扣教材基础知识，旨在巩固学生的基础，提高学生的应试能力。该题的关键是明确反应的原理，然后依据反应的化学方程式计算即可，有利于培养学生的逻辑推理能力和创新思维能力。
As we know, Xiao Shenyang and Liu Qian did wonderful jobs in the CCTV Spring Festival Gala. Now many people are crazy about these two persons. But how much do you know about them
Xiao Shenyang was born in a poor peasant family which is in difficult family conditions. His real name is Shen He. He is an actor. He is good at Er Ren Zhuan. He learned acts, following Zhao Benshan. During the school life, he was very active in many activities. He looks like a simple man, but he never stops pursuing his artistic aspiration. More and more people like his style of performance, and we hope he can make great progress in the future.
Liu Qian is a young magician from Taiwan. At the age of 7, Liu saw a cute magic toy in a shop.
At that moment he began to love and decided to learn magic. Liu didn’t go to any magic school. He practiced tricks every day to improve his skills, until one day he was able to put on a show for his class. He saw the surprise on everyone’s face, and he felt it was cool. He often does street shows for passers-by, police and farmers. He worked hard at it. Now he is a famous magician.
根据短文内容完成下面表格中由于小沈阳和刘谦的信息
| Xiao Shenyang | Liu Qian |
| Job | An actor | A young magician from Taiwan |
| How to succeed | He learned acts, (56) Zhao Benshan. During the school life, he (57) He looks like (58) . But he never stops pursuing the artistic aspiration. | He always learned magic (59) at the beginning. At his show for his class, he found everyone (60) and he felt it was cool. He often does street shows for people. He works hard at it. |
