问题 选择题

一定温度下,2SO2(g)+O2(g)⇌2SO3(g);△H=-197kJ/mol,将3molSO2和1molO2充入一定容密闭容器中,在催化剂存在下进行下列反应,当达到平衡状态时,下列说法中正确的是(  )

A.生成SO3为2mol

B.SO3和SO2物质的量之和一定为3mol

C.放出197kJ的热量

D.SO2的物质的量和SO3物质的量一定相等

答案

A、该反应为可逆反应,1mol氧气完全反应才能生成2mol二氧化硫,由于可逆反应不可能完全转化成生成物,所以生成的三氧化硫的物质的量小于2mol,故A错误;

B、根据质量守恒,含有硫原子的物质只有二氧化硫和三氧化硫,反应前有3mol二氧化硫,所以SO3和SO2 物质的量之和一定为3mol,故B正确;

C、热化学方程式中:2SO2(g)+O2(g)⇌2SO3(g);△H=-197kJ/mol,反应消耗1mol氧气能够放出197kJ热量,由于可能反应中反应物转化率不可能是100%,所以反应中放出的热量小于197kJ,故C错误;

D、达到平衡状态,满足正逆反应速率相等,各组分的浓度不变,而SO2的物质的量和SO3物质的量不一定相等,故D错误;

故选B.

完形填空

Teenagers who spend hours in front of the television may have a poorer diet, a new study shows. It is not clear, researchers say, whether television itself is the reason, but it is possible that things like snacking in front of the TV or seeing ads for junk food influence young people’s diets.

The study included nearly 1,400 high school students. It showed that those who watched TV for five hours or more every day had less healthy diets than other students five years later. As a group, they ate fewer fruits and vegetables, but ate more fast food, snack products and fried foods.

“We’re not able to tell why,” lead researcher Dr. Daheia J. Barr-Anderson said. “But we have some speculation(推测).” People who spend a lot of time in front of the TV, especially teenagers, may have more snacks. It may influence their long-term diet quality. It’s also possible that TV ads for fast food, sweets and snacks make teenagers eat more of those foods. TV time might also replace exercise time for some kids.

The researchers found a clear relationship between TV time during high school and diet quality of the young. The heaviest TV viewers ate the most junk food five years later, and those who’d watched fewer than two hours every day had the most fruits and vegetables.

According to Barr-Anderson, the findings support experts’ advice that children should watch no more than two hours of television every day. “Parents should cut the TV time.” Barr-Anderson said. She advised that parents set a good example by eating right, being physically active and controlling their own TV time.

小题1:Is it clear that television is the reason for young people’s poor diet?

(no more than 3word)

(2 marks)

小题2:What kind of TV ads will makes teenagers eat more unhealthy food?

(no more than 10 words)

(2 marks)                                                            

小题3:According to Barr-Anderson, what should parents do to set a good example for their children? (no    more    than    15  words)                                                   (3 marks)                                                                                                                                              

小题4:What is the passage mainly about?  (no more than 10 words)            

(3 marks)

单项选择题 A型题