问题 填空题

化学是研究物质的组成、结构、性质及变化规律的科学。

(1)锌、干冰、氯化钠3种物质中,由离子构成的是    

(2)食醋中含有醋酸(CH3COOH),醋酸中氢、氧元素的质量比为    (结果用最简整数比表示)。

(3)碳酸氢钠可用于治疗胃酸过多,用化学方程式表示其原因  _______  

(4)为维护食品安全,卫生部禁止在面粉中添加增白剂,如过氧化钙(CaO2)等。过氧化钙中氧元素的化合价是    ,它和水反应能生成一种碱和氧气,反应的化学方程式是    __________

答案

(1)氯化钠        (2)1∶8

(3)NaHCO3 + HCl = NaCl + H2O + CO2↑ (4)-1   2CaO2 + 2H2O = 2Ca(OH)2 + O2

(1)锌属于金属,是由原子直接构成的;干冰是固态二氧化碳,由二氧化碳分子构成;氯化钠是由钠离子和氯离子构成的;

(2)由醋酸(CH3COOH)的化学式可知,醋酸中氢、氧元素的质量比=(14):(162)=1:8.

(3)胃酸的主要成分是盐酸,碳酸氢钠与盐酸反应生成氯化钠、水、二氧化碳,反应的化学方程式为NaHCO3 + HCl = NaCl + H2O + CO2↑.

(4)碳钙氧元素显+2,设氧元素的化合价是x,根据在化合物中正负化合价代数和为零,可知过氧化钙(CaO2)中氧元素的化合价:(+2)+2x=0,则x=-1.

根据题意,过氧化钙(CaO2)和水反应能生成一种碱和氧气,根据质量守恒定律可知,生成的碱是氢氧化钙,反应的化学方程式为2CaO2 + 2H2O = 2Ca(OH)2 + O2↑.

阅读理解

My parents divorced when I was 8 years old. Their marriage was a mistake of World War II. And about 50 years ago, I was the only child I knew who didn't have a father at home on Father's Day. Divorce was very uncommon back then.

So when my friends were in town shopping for presents for their fathers, I decided since my mother was both Mother and Father, no one else was like her, who better deserved(be worth) a present on Father's Day than her?

I bought her a little set of tools, just a few things, hammer, pliers(钳子) and screwdriver(螺丝起子) and a box to put all these things in. I got some ideas from my grandfather and named it Mother's Tool Box. She was excited, more at the thought of being cared for on Father's Day than of the present. She always said she liked her Father's Day memories better than the Mother's Day ones. It made her feel special — and she was. I have noticed in the past few years, greeting cards are even made for "Mother on Father's Day". Ever since then, my mother has got cards on Father’s Day. By the way, she knew just how to use those tools and others she had ever used over the years.

小题1:Which sentence shows that divorce was very uncommon at that time?

A.My parents divorced when I was 8 years old.

B.My parents’ marriage was a mistake of World War II.

C.My mother has got cards on Father’s Day.

D.I was the only child who didn’t have a father at home on Father’s Day.小题2:What did the writer decide to do when he saw friends shopping for Father’s Day presents?

A.Go shopping with his friends.

B.Buy a present for his mother.

C.Help his mother.

D.Ask his grandfather for help.小题3:“Hammer, pliers and screwdriver” are probably things __________.

A.more often used by men

B.that cost a lot of money

C.very popular at that time

D.that his mother liked most小题4:Mother was excited because __________.

A.she was very interested in the tool box

B.she was deeply loved by her child

C.she saw the name on the tool box

D.she knew how to use the things小题5:Why did Mother feel special?

A.She had more Father’s Day memories.

B.She had only one child.

C.She was both Mother and Father.

D.She was the happiest one on Father’s Day

单项选择题