问题 选择题

在一定温度和压强下,2体积X2气体与3体积Y2气体恰好完全反应,生成2体积气体化合物Z,则Z的化学式可能是(  )

A.XY3

B.XY

C.X3Y

D.X2Y3

答案

一定温度和压强下,体积之比等于物质的量之比,也等于化学计量数之比,

由2体积X2气体与3体积Y2气体恰好完全反应,生成2体积气体化合物Z,

则2X2+3Y2═2Z,

根据质量守恒定律可知,反应前后的原子个数相等,

所以Z的化学式为X2Y3

故选D.

单项选择题
单项选择题

Everyone gets angry sometimes, but being angry doesn’t really solve much. Your goal is to calm yourself down. This is (1) for some people. Instead of calming down, they might get more and more upset (2) they explode like a volcano. Some people might say they have trouble (3) their temper. Sometimes angry feelings can be hard to (4) . So what do you do if your temper is like a volcano

Well, the good news is (5) people don’t keep making the same mistakes over and over again. You can train your temper. Here are steps you can (6) at any time.

Get a lot of (7) activity. Exercise can be good because it is a way of (8) energy and stress. You can dance around your room (9) your favorite music, too.

Talk to your mom or dad. If you’re having trouble with your temper, tell your parents you’re trying to do a (10) job of controlling yourself. Let them know you are going to ask for their help.

Put (11) into words. Get into the habit of saying what you are feeling and why. (12) using words might help you manage your p feelings and behaviors.

Take a break from the (13) . If you are in an argument with someone, go to another part of your house. You can just say, "I want to be (14) for a while so I can calm down. "

Go into a (15) . If you fed angry and think you need a timeout to calm down, don’t (16) your parents to tell you to take a timeout for yourself. Let your family know that when you’re taking a timeout, they need to (17) your space and leave you alone. While you are sitting in your chair, try to take deep (18) .

Learn to shift. The idea is to shift from a really angry mood to a better mood. After you (19) the angry feelings out, you have to start thinking about other things, You can say, "I (20) my temper, but I’m going to get myself under control now.

7()

A.physical 

B.mental 

C.scientific 

D.spiritual