name and explain the property of a material that can be easily depicted by closing our eyes
Answers
Explanation:
Hardness
When you press different materials with your hands, some of them may be hard to compress while others can be easily compressed. Take a metal key and try to scratch with it, the surface of a piece of wood, aluminium, a piece of stone, a nail, candle, chalk, any other material or object. You can easily scratch some materials, while some cannot be scratched so easily. Materials which can be compressed or scratched easily are called soft while some other materials which are difficult to compress are called hard. For example, cotton or sponge is soft while iron is hard.
In appearance, materials can have different properties, like lustre, hardness, be rough or smooth. Can you think of other properties that describe the appearance of a material?
Soluble or Insoluble?
Activity 4
Collect samples of some solid substances such as sugar, salt, chalk powder, sand and sawdust. Take five glasses or beakers. Fill each one of them about two thirds with water. Add a small amount (spoonful) of sugar to the first glass, salt to the second and similarly, add small amounts of the other substances into the other glasses. Stir the contents of each of them with a spoon. Wait for a few minutes. Observe what happens to the substances added to water (Fig. 4.4).
Note your observations as shown in Table 4.3.
Fig. 4.4 What disappears, what doesn’t?
Table 4.3 Mixing different solid materials in water
You will notice that some substances have completely disappeared or dissolved in water. We say that these substances are soluble in water. Other substances do not mix with water and do not disappear even after we stir for a long time. These substances are insoluble in water.
Water plays an important role in the functioning of our body because it can dissolve a large number of substances.
Do liquids also dissolve in water?
Activity 5
Collect samples of vinegar, lemon juice, mustard oil or coconut oil, kerosene or any other liquid. Take a glass tumbler. Fill it up to half with water. Add a few spoonfuls of one liquid to this and stir it well. Let it stand for five minutes. Observe whether the liquid mixes with water (Fig. 4.5). Repeat the same with other liquids, as many different liquids as are available to you. Write your observations in Table 4.4.
Answer:
Reflected rays is the answer
Explanation:
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