问题 填空题

(1)某肉制品包装上印有相关配料:精选瘦肉、食盐、亚硝酸钠、苯甲酸钠。其中属于调味剂的是____,属于发色剂的是____,属于防腐剂的是____。

(2)亚硝酸钠有毒,其外观和咸味与食盐很相似,因此要防止因误食亚硝酸钠而发生事故。亚硝酸钠和氯化钠的部分性质如下表:

请根据表中信息设计一种鉴别NaNO3和NaCl的方法,写出简单的操作过程、现象和结论:_____________

答案

(1)食盐;亚硝酸钠;苯甲酸钠(或苯甲酸钠和亚硝酸钠)

(2)溶于水制成溶液,加入稀硫酸微热,有棕色气体生成者,原物质为NaNO2,否则为NaCl(或用酒精灯加热,熔化者为NaNO2,不熔者为NaCl;或取两点试管,各加入5mL水,分别溶解这两种物质,至不再溶解时,溶解量大的为亚硝酸钠,溶解量小的为氯化钠)

阅读理解

阅读理解。

     Time Temp Glasses

     Are you a person who wants to know the time and temperature during the day? You might like Temp

Glasses. These special glasses show the time above your right eye and the temperature your left eye. It is

surely easier than wearing a wristwatch, and you never have to guess the Tature.

     Alarm Fork

     Do you eat too quickly? Do you eat too much? How can the Alarm Fork help you? Aren't you is (好奇的)?

Well, this special fork has two lights: one green and one red. When the green is on, it's ok to eat a piece of

food. The fork "knows" when you eat a piece, and soon the red goes on. Wait for the green light before you

eat another piece.

      Smell This

      Sow do you know if your breath smells nice, or if it smells bad? It's difficult to know, because it's very

hard to smell the air that comes out of your own mouth. Smell This is useful for this ion. Smell This covers

your nose and your mouth. Docs your breath smell nice, or do you need a piece of gum (口香糖)?

      Banana Suitcase (手提箱)

      Has this ever happened to you? You put a banana in your bag lunch in the morning, and when pen the

bag at noon, the banana looks like someone drove a car over it. If you put your banana Banana Suitcase, this

will never happen. It keeps a banana safe, delicious, and looking like new!

1. The writer thinks that the four inventions are ________.

A. dangerous

B. useless

C. unusual

D. expensive

2. A person who wants to lose weight may be interested in ________.

A. Time Temp Glasses

B. Alarm Fork

C. Smell This

D. Banana Suitcase

3. Which invention is most helpful for someone waiting for a train?

A. Time Temp Glasses.

B. Alarm Fork.

C. Smell This.

D. Banana Suitcase.

4. If you want to know how your breath is. you may buy ________.

A. Time Temp Glasses

B. Alarm Fork

C. Smell This

D. Banana Suitcase

5. Who might use the Banana Suitcase?

A. A person who eats bananas only at home.

B. Someone who needs to throw away a banana.

C. A person who has little interest in eating bananas.

D. Someone who loves bananas and brings lunch to school every day.

填空题