问题 选择题

如图,Ⅰ是恒压密闭容器,Ⅱ是恒容密闭容器。

其它条件相同时,在Ⅰ、Ⅱ中分别加入2mol X和2mol Y,起始时容器体积均为V L,发生如下反应并达到平衡(X、Y状态未知):3X(g)+Y(g)2 Z(g)。此时Ⅰ中X、Y、Z的物质的量之比为1:3:2,则下列说法一定正确的是(   )

A.平衡时气体的平均摩尔质量:M(Ⅰ) <M(Ⅱ)

B.平衡时气体的密度:ρ(Ⅰ)>ρ(Ⅱ)

C.平衡时Ⅰ和Ⅱ中Z的百分含量z%(Ⅰ) > z% (Ⅱ)

D.平衡时气体的压强P(Ⅰ)<P (Ⅱ)

答案

BC

该反应是体积是减小的可逆反应,所以压强也是减小的,因此反应Ⅰ中的压强始终大于反应Ⅱ中的压强,D不正确。压强大,有利于平衡向正反应方向移动,即Ⅰ中反应物的转化率高,C正确。气体的总的物质的量少,混合气的平均相对分子质量是混合气的质量和混合气的总的物质的量的比值,质量不变,所以M(Ⅰ)>M(Ⅱ),A不正确。密度是混合气的质量和容器容积的比值,在反应过程中质量是不变的,所以ρ(Ⅰ)>ρ(Ⅱ),C正确。答案选BC。

阅读理解

                                            Safety and Security Procedures

  Your safety and the security of your personal property are of the primary concern to those of us who

welcome you as our guest. We urge you to take advantage of the following suggestions.

  YOUR VEHICLE

  Lock your vehicle and do not leave money or valuable items inside. We are not responsible for their

loss.

  TRAVELING

  Be good at noticing things around you when sightseeing or traveling. Stay in well-lit and heavily traveled

areas. Don't display large amounts of cash.

  GUEST ROOM SECURITY

  For additional security use the deadbolt (插锁) provided on your door and make sure the windows are

locked. As an additional precautious measure, please secure the secondary locks provided. Do not admit anyone to your room without first making identification. A one-way viewer is provided in your door to

assist with identification. If there is any doubt about the person's identity, please contact the Front Desk.

SAFETY BOXES

  Do not leave money or valuables in your room or vehicle. We provide free safety boxes for your use.

Hotel is not responsible for items left in room valued over $200.

KEYS

  Safeguard your key. Please do not leave it in the door. Do not give your key to others or leave it

unattended. Please leave your key at the Front Desk when you check out.

REPORTING

  Please report any suspicious activity, or safety concerns to management.

FIRE

  Please familiarize yourself with the nearest fire exits. Report fire or smoke to the hotel operator. In the unlikely event of a fire, please move quickly and calmly to the nearest safe exit and leave the building. Avoid the use of elevator.

1. The suggestions are most probably from ______.

A. a hotel manager      

B. a police officer  

C. an experienced traveler    

D. a tour guide

2. Which of the following is TRUE?

A. It is advised to travel to places where there are few people.

B. The hotel is not responsible for anything you lose.

C. Don't report to the manager unless you are sure something is going wrong.

D. You'd better use the deadbolt and the secondary locks for safety.

3. If you feel doubtful about a stranger who knocks at the door, you should _____.

A. let the person in after you have got his/her name

B. open the door to check the person's ID card

C. call the Front Desk to make sure D. contact the local police for assistance

4. What does the underlined part "In the unlikely event of a fire" mean?

A. In case a fire happens, though it is not very possible

B. If a fire happens when some big events are taking place.

C. In case a fire happens in a public building.

D. If a fire breaks out and it is getting out of control.  

单项选择题