GROUPING MATERIALS NOTEBOOK WORK TEXTBOOK Q -ANS
Answers to the questions given in check your progress: (page number 36)
1. Why do we classify materials?
Classification helps in identification, sorting objects, locating things, etc
2. Which property of gases helps us in detecting leakage in cooking gas?
It does not have a specific shape and specific volume hence it occupies the space of the
container or room. During leakage of cooking gas, the gas occupies the space of the
room and can be easily detected.
Answers to the questions given in check your progress: (page number 39)
1. Classify the following into three groups – transparent, translucent and opaque.
2. How do we decide that an object will float or sink in a liquid?
If the density of the object is less than the density of liquid, the object will float.
If the density of the object is more than the density of liquid, the object will sink.
Answers to the questions given in let’s exercise
1. Choose the correct option:
a. Which of the following materials is translucent?
Ans: Cotton cloth
b. The phenomenon exhibited by glass, thin layer of air and water is known as
Ans: Transparency
c. Which of the following properties is not true about a piece of rock?
Ans: It has lustre
d. Gycerine and water are
Ans: Miscible liquids
e. Identify the materials which are soft:
Ans: All of these
2. Fill in the blanks.
a. The materials that do not allow light to pass through them are called opaque materials.
b. The molecules in solids are tightly packed.
c. If a solid disappears in water, the solid is said to be soluble in water.
d. Liquids have a definite volume but no definite shape.
3. State whether the following statements are True (T) or False (F).
a. Rubber is transparent while water is opaque. False
b. Kerosene mixes with water. False
4. Answer the following questions in one word or one sentence.
a. Name the type of material which allows light to completely pass through it. Transparent
b. How are materials classified on the basis of the amount of light that passes through them?
Transparent, translucent and opaque.
c. What is the gentle sheen or soft glow possessed by a material known as? Lustre
5. Answer the following questions in short.
a. What do you mean by properties of a material?
Features or characteristics of a material such as its strength, transparency,
conduction, etc. are called its properties.
b. How are materials grouped?
We group objects on the basis of certain similarities and dissimilarities in their
properties.
c. Explain the factor on which the sinking or floating of an object depends.
A substance will only ß oat if its density is less than that of the surrounding liquid. It
will sink if its density is greater than that of the surrounding liquid.
6. Give reasons.
a. A piece of wood floats in water.
The piece of wood has a density lower than water hence it floats in water.
b. We can see through air but not through a book.
Air is transparent and book is opaque.
7. Answer the following questions in detail.
a. What are the advantages of classification?
It helps in identification, sorting, locating things. It makes the study of different
objects easy and more meaningful and helps to understand similarities and
dissimilarities among the objects.
b. Explain miscible and immiscible liquids giving suitable examples
When two liquids mix with each other or dissolve each other, they are known as
miscible liquids.
The liquids which do not mix with each other are known as immiscible liquids.
c. Discuss solubility of solids, liquids and gases in water with the help of examples.
The substances which disappear or dissolve completely in water are called soluble
substances. The substances which do not dissolve in water are called insoluble substances.
8. HOTS (Higher Order Thinking Skills)
a. We know that metals sink in water. Why do large ships made up of metal float on water?
It won't sink because the entire structure still weighs less than the water upon which it
floats.
.
9. Value based questions
Sohail and Shashi are best friends. They opened retail shops in their hometown. They bought
similar articles in wholesale from the city and sold them at the same price. Sohail used to have
brisk sales. However, customers were not happy with Shashi. Many a times he could not locate
the articles dumped in the shop.
Answer the questions based on the above information.
a. What are the values displayed by Sohail?
Sohail was good in organising and grouping things in the shop.
b. What was the problem with Shashi? Discuss. [Assume both of them were nice to their
customers.]
Shashi many a times could not locate the articles dumped in the shop.
c. Suggest ways to improve the retail sales of Shashi.
Shashi should learn grouping and classifying the objects in the shop based on their
properties.
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