题目内容

【题目】小英在做饭时,发现有很多因素都能影响食盐在水中溶解的速率.

(1)从你能想到的可能影响食盐在水中溶解速率的因素中,写出其中两项,并预测此因素对食盐的溶解速率的影响.

因素________,你的预测________________.

因素________________,你的预测________________.

(2)从你所列因素中选出一个,并通过实验验证你的预测.________________________

【答案】(1)温度 温度升高(或温度降低),食盐溶解速率加快(或减慢) 晶体颗粒大小 食盐颗粒越小,溶解越快 搅拌 搅拌能加快食盐的溶解(任选两项)

(2)搅拌因素的影响:在两个烧杯中各加入50mL水,分别称取2g颗粒大小相同的食盐,同时放在以上两个烧杯中,在一个烧杯中搅拌,在另一个中不搅拌,观察并记录两个烧杯中的食盐完全溶解所需的时间(同理可设计温度、颗粒大小对溶解速率影响的实验)

【解析】根据生活中的观察,可想到影响食盐在水中溶解速率的因素有温度、食盐晶体颗粒大小、是否搅拌等.可通过设计对比实验加以验证.

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【题目】C

People eat different things in different parts of the world.

In some countries, people eat rice every day. Sometimes they eat it two or three times a day for breakfast, lunch and supper. They eat rice with meat, fish and vegetables. Some people do not eat some kinds of meat. Muslims(穆斯林), for example, do not eat pork. Japanese eat lots of fish. They are near the sea. So it is easy for them to get fish.

In Western countries such as Britain, Australia and the USA, the most important food is bread and potatoes. People there can cook potatoes in many different ways.

Some people eat only fruit and vegetables. They do not eat meat or fish or anything from animals. They eat only food from plants(植物). Some people say that food from plants is better than meat. These people are called vegetarians.

【1】 What does the underlined word vegetarians mean in Chinese?

A. 肉食主义者 B. 生食主义者

C. 果食主义者 D. 素食主义者

【2】__________ do not eat pork.

A. Chinese B. Japanese

C. Muslims D. Americans

【3】 Why do Japanese eat lots of fish?

A. Because they like fish better than the other food.

B. Because it is easy for them to get fish.

C. Because fish can give them lots of calories.

D. Because they think eating fish can make them clever.

【4】 What is the most important food in Australia?

A. Fish. B. Bread. C. Vegetables. D. Fruit.

【5】Which one of the following sentences is true?

A. People in different countries eat different food.

B. If you only eat food from animals, you are a vegetarian.

C. Food from animals is better than food from plants.

D. People in some Western countries can only cook potatoes in one way.

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