题目

在化学晚会上，小李表演了一个魔术，大家观察到小李将甲、乙两烧杯中的溶液各自分成了两等份，并按下图的流程表演了两次，但却出现了两种不同的现象。(友情提示：1．表演中产生的气体无色无刺激性气味；2．可溶性钡盐对人体有毒。要避免误食．) 回答下列问题： （1） 反应①产生的气体的化学式是； （2） 写出反应②的化学方程式； （3） 若出现现象一，写出那杯白色浑浊的“牛奶”中所有成分的化学式：； （4） 反The next time you get caught jumping on your bed you can tell your parents with a straight face that you are not playing, simply getting ready got a promising career in “Mattress Jumping”. Believe it or not, there are some people who actually get paid to do that! According to Reuben Reynoso, a professional mattress tester at San Francisco’s McRoskey Mattress Factory that still makes every mattress by hand, it is real work and needs some training. For a start, it’s not all about jumping to new heights or doing tricks like professional athletes, but rather about feeling each area of the mattress carefully to detect the filling. In order to do it right, every bit of the mattress has to be tested slowly and deliberately.Over the years, Reynoso has figured out the perfect routine. He begins by placing a protective mat over the mattress so that it doesn’t get dirty or absorb the smell from his feet. Then begins the fun---he steps to the middle of an edge and then takes five steps back and five steps forward. In this way, he slowly but surely, covers the entire surface. The key according to him is to find the perfect number of jumps---Too many and he will end up destroying the mattress completely. Too few And it will not fit into the giant machine for that final sewing! Who knew a job that sounds so simple could have so many skills!While Reuben will not reveal how he got into this profession, he will admit that it is more fun than being a carpenter, roofer, construction worker and railroad engineer---all jobs he has tried previous to finding his true profession!1.We learn from the text that the McRoskey Mattress Factory ______.A. is the world’s oldest mattress factoryB. make mattresses for sportsC. produces mattresses by handD. hires athletes as mattress testers2.The protective mat is used to ______.A. prevent the tester getting hurtB. keep the mattress as clean as possibleC. protect the mattress from being destroyedD. make the mattress fit into the sewing machine3.According to Reynoso, the most important thing in his work is ______.A. the timing of his jumps B. the height of his jumpsC. the number of his jumps D. the frequency of his jumps4.We can learn from the text that Reynoso ______.A. has been injured several times in his workB. liked mattress jumping in his childhoodC. didn’t choose mattress testing as his first jobD. dreamt about becoming a jumping athlete