用元素符号或化学式填空 ①5个二氧化碳分子②氦气③3个钾原子④_爱下问搜题

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问题填空题

用元素符号或化学式填空

①5个二氧化碳分子 ②氦气 ③3个钾原子 ④钠离子 ⑤4个硫酸根离子 ⑥标出NaClO中氯元素的化合价

答案

① 5CO₂ ② He ③ 3K ④ Na⁺⑤ 4SO₄^2- ⑥ +1

题目分析：根据化学符号及其周围数字的意义分析解答。

（1）标在化学式前面的数字表示分子的个数，故5个二氧化碳分子表示为5CO₂；

（2）氦气属于稀有气体单质，是直接用元素符号表示其化学式的，故其化学式为He。

（3）标在元素符号前面的数字表示原子的个数，故3个钾原子表示为3K；

（4）标在元素符号右上角的数字表示离子所带电荷数，且数字在前，正负号在后，“1”要省略；由于钠离子带一个单位的正电荷，故表示为Na⁺；

（5）标在离子符号前面的数字表示离子的个数，故4个硫酸根离子表示为4SO₄^2-；

（6）标在元素符号正上方的数字表示该元素化合价的数值，由于NaClO中氯元素的化合价为+1价，故表示为。

点评：本题难度不大，主要考查了元素符号不同位置的数字表示的意义，掌握标在元素符号不同位置的数字所表示的意义是正确解答此类题的关键所在。

问答题

　　从今年5月1日起，我国在室内公共场所实行全面禁烟，请你为校园内的“禁烟提示牌”编写一条温馨提示语。

　　要求：①符合场景；②语言表达简明、生动、得体；③不超过20个字。

答：____________________________________________。

完形填空

I have a friend who had a stammer (口吃) in his childhood, but he dreamed of becoming a missionary(传教士). When he told his own desire to his friends and relatives, some of whom laughed at him, and some even held down his enthusiasm       .
"I must change it." said the boy angrily, “I believe I can speak very      , I will do!"
When it was possible, he would spend an hour       to chickens. He viewed the chickens as living persons,       himself to be the person in the speech.
"In the beginning, the chickens looked so      , then they watched me curiously, putting down the food in the mouths and listening to my words. It seemed as if they had been     by my powerful and effective language. Sometimes they seemed to be listening to me    . Gradually, the effect of this practice became more and more     and I had a better understanding of the exact     of my stammer, so I found the ability to speak more."
"You may not know that my father was always tyrannical(专横的). He     believed in the old saying: 'Young man should be more knowledgeable, but should not    much.' During the whole childhood,      I spoke or commented, he criticized me seriously, which    my shy personality. I used to worry about being     at, so I became a stammer. From then on, I kept    in front of everyone because they didn't want to see my embarrassment. But later I found myself talking in front of chickens, stammers disappeared  , therefore I regained my   ."
Now, the previous boy is the best at speaking and one of the most     missionaries. You can hardly imagine he used to have a serious language    . So when you come across disadvantages, you should believe you can      them by yourself.

A．contributing

A．considering

C．referred to

A．intelligent

D．responsible