问题 单项选择题

工程上常把导热系数入值()的材料称为绝热材料。

A.小于0.25W/(m·k)

B.小于0.3W/(m·k)

C.大于0.25W/(m·k)

D.大于0.3W/(m·k)

答案

参考答案:A

问答题

Ⅰ:由于温室效应和资源短缺等问题,如何降低大气中的CO2含量并加以开发利用,引起了各国的普遍重视.目前工业上有一种方法是用CO2生产燃料甲醇.一定条件下发生反应:CO2(g)+3H2(g)⇌CH3OH(g)+H2O(g),△H<0

(1)该反应平衡常数K的表达式为______.温度降低,平衡常数K______(填“增大”、“不变”或“减小”).

(2)为探究反应原理,现进行如下实验:在体积为1L的密闭容器中,充入1molCO2和3molH2,测得CO2和CH3OH(g)的浓度随时间变化如图1所示.从反应开始到平衡,用氢气浓度变化表示的平均反应速率v(H2)为______.

(3)下列措施中能使n(CH3OH)/n(CO2)增大的有______.

A.升高温度;B.加入催化剂;C.将H2O(g)从体系中分离;D.再充入1mol CO2和3mol H2

E.充入He(g),使体系总压强增大.

(4)如图2所示,在甲、乙两容器中分别充入物质的量之比为1:3的CO2和H2,使甲、乙两容器初始容积相等.在相同温度下发生反应,并维持反应过程中温度不变.甲和乙相比,转化程度更大的是______,且知乙容器中CO2的转化率随时间变化的图象如图3所示,请在图3中画出甲容器中CO2的转化率随时间变化的图象.并请说明以CO2为原料生产燃料甲醇的优点是______(写出一条即可).

Ⅱ:一定常温下,FeS的KSP=2.5×10-18,H2S饱和溶液在该温度下,[H+]与[S2-]存在着以下关系:[H+]2•[S2-]=1.0×10-21.在该温度下,将适量FeS投入H2S饱和溶液中,欲使溶液中[Fe2+]达到1mol/L,应调节溶液的pH为______(用对数形式表示).(写出计算过程)

阅读理解

阅读理解。

     Whenever the sun dropped and the blue sky came up, my father and I used to climb the mountain near my

house. Walking together, my father and I used to have a lot of conversations through which I learned lessons

from his experiences. He always told me,"You should have goals like climbing the mountain." Without the

mountain-climbing that we both enjoyed, we couldn't have enough time to spend together because my father

was very busy. I really got a lot from the mountain-climbing. It gave me time to talk with my father and to be

in deep thought as well as develop my patience.

     Once we climbed a very high mountain. It was so challenging for me because I was only ten years old.

During the first few hours of climbing, I enjoyed the flowers and trees, and the birds' singing. But as time

passed, I got a pain in both of my legs. I wanted to quit climbing, but my father said to me, "You can always

see a beautiful sky at the top of the mountain, but you can't see it before you reach the top. Only there can you

see all of the nice things, which is just like your life."

     At that time, I was too young to understand his words. But later after that, I got to know the meaning of

hope in life. I found myself standing at the top of the mountain, and the sky was as clear as crystal.

1. The passage tells us that mountain-climbing was ______ for the father and the son.

A. hard

B. enjoyable

C. painful

D. comfortable

2. The underlined word "crystal" in the passage means _______.

A. 岩石

B. 火焰

C. 水晶

D. 寒冰

3. Which of the following is the closest in meaning to the father's words in the second paragraph?

A. You will get all you need at the top of the mountain.

B. The sky is always as clear as crystal.

C. You can find life is full of nice things.

D. Never give up half-way.

4. We can infer(推断) from the last paragraph that ______.

 A. the writer was very successful in his life

B. the writer reached the top of the mountain

C. though the writer was young, he could understand his father

D. the writer used to stop half-way when he climbed the mountain

5. The best title for the passage is ______.

A. Reaching the Top of the Mountain

B. Standing at the Top of the Mountain

C. Conversations between Father and Son

D. How to Get to the Top of the Mountain