问题 计算题

酒精是常用的液体燃料,酒精的化学式C2H5OH.试计算:

(1)酒精的相对分子质量是多少?

(2)酒精分子中的碳、氢、氧三种原子的个数比是多少?

(3)酒精中的碳、氢、氧三种元素的质量比是多少?

(4)9.2g酒精中含氢元素的质量为是多少g?

(5)多少g的酒精所含碳元素质量与8.8g二氧化碳所含碳元素质量相等?

答案

(1)12×2+1×5+16+1=46.

(2)2:6:1.

(3)(12×2):(1×6):(16×1)=12:3:8.

(4)9.2g酒精中含氢元素的质量为9.2g××100%=1.2g.

(5)设所需酒精的质量为x,由于所含碳元素的质量相等,则x××100%=8.8g×100%,解得x=4.6g.

完形填空

缺词填空(根据短文内容及首字母提示,填入所缺单词)(共10空,每空1分,满分10分)

Many books have been written about “the art of giving”. But what about the art of r  1 ? Sometimes, receiving a gift can be difficult, especially when someone buys you a gift you don’t want!

“I remember when I was about twelve years old, my parents b  2  me a purple purse,” laughs Guo Xiaojing. “It really made me feel embarrassed(尴尬), because I thought the purse was really ugly!Still, I pretended (假装)that I liked it b  3  I knew it would make my parents happy!”

Han Ling agrees. “That sounds like my grandparents!A few years ago, my grandparents gave me an orange sweater f  4  my birthday. I used to wear it every time I visited them, but when I left their house, I took it off! Of course, this made me feel g  5 . It was a very nice thought, but my grandparents have different taste from me! I think it’s hard to buy clothes or other personal things for people.”

To make things easier, some people would rather just give money. In some cultures, h  6  , receiving money can make people uncomfortable. “When someone gives me money, it j   7   makes me think they’re being lazy,” says John Wilson. “In England, we have a saying: It’s the thought that counts. When s   8   gives me money, I feel they don’t think at all. I prefer to receive a gift that has some thought behind it. I don’t mind if it’s something I don’t need. If someone has thought about a g   9  for me, it always makes me happy.”

Different people have very different thoughts on this subject! So maybe the art of receiving is e 10  more difficult than the art of giving! What do you think?

问答题 简答题