Question 1: Column ’A’ Column ’B’ 1. Fluoride a. Man-made detergent 2. Soap nut b. Sodium salt of fatty acid 3. Soap c. Man-made material 4. Cotton d. Prevents tooth decay 5. Nylon e. Potassiu

Column ’A’ Column ’B’ 1. Fluoride d. Prevents tooth decay 2. Soap nut f. Natural detergent 3. Soap a. Man-made detergent 4. Cotton g. Natural material 5. Nylon c. Man-made material 6. Hard soap b. Sodium salt of fatty acid 7. Calcium carbonate h. Main ingredients of toothpaste 8. Soft soap e. Potass

Question 1: What is the source of the fluoride in a tooth paste or tooth powder?

A naturally occurring mineral found in tooth paste and drinking water. Sodium Fluoride (NaF) is the source of fluoride in toothpaste.

Question 2: Note down all the information given on a tooth powder/toothpaste container or carton and discuss.

1. The carton shows the name of the company and name of toothpaste and its contains all the ingredients present in toothpaste.

Question 3: Now a days why are the roads made of concrete?

Step-by-step solution provided.

Question 4: What causes the hardness of water?

Step-by-step solution provided.

Maharashtra State Board Class 7 Science & Technology Solutions Chapter 15 Materials We Use - Digest Answers | Maharashtra Board Solutions

Maharashtra State Board Class 7 Science Solutions Chapter 15 Materials We Use

Class 7 Science Chapter 15 Materials We Use Textbook Questions and Answers

1. Fill appropriate terms in the blanks:
(white cement, soap, detergent, wearing of bones, tooth decay, hard, soft, portiand, fatty acid)

Question a.
The substance that helps water to remove dirt from the surface of material is called …………….
Answer:
soap

Question b.
Fluoride is used in toothpaste to prevent …………….
Answer:
tooth decay

Question c.
Soap is a salt of …………… and sodium hydroxide.
Answer:
fatty acid

Question d.
Synthetic detergents can be used in …………… water as well.
Answer:
hard

Question e.
For construction purposes …………… Cement is the most commonly used cement.
Answer:
white cement

2. Write answers to the following questions.

Question a.
How does the use of a detergent help to clean soiled clothes?
Answer:

Question b.
How will you check with the help of soap powder whether water is hard?
Answer:

Question c.
What are the important ingredients of a tooth paste and what is the function of each?
Answer:

Question d.
What are the ingredients of cement?
Answer:

Question e.
What will happen if cement is not used in making concrete?
Answer:

Question f.
Make a list of detergents, that you use. Answer: There are two types of detergents that we use, (a) Natural (b) Man-made detergents.

Question g.
What should be expected from a detergent for delicate garments?
Answer:

Question h.
What is meant by surface activity? Name three chemicals responsible for the surface activity of various detergents.
Answer:

3. What are the similarities and differences between:

Question a.
Natural detergents and Man-made detergents
Answer:

Natural detergents	Man-made detergents
1. Soap nut (ritha) and soap pod (shikekai) are the natural detergents.	1. Soap is man-made detergent soft soap and hard soap.
2. Natural detergents do not have harmful effect on human skin or on silk or woollen clothes.	2. Soap has effect on skin and cloth because it has chemicals in it.
3. Soap nut, soap pod contain a chemical saponin.	3. Soap has acid in it, soap is sodium and potassium salt of fatty acids.
4. It is naturally available.	4. It is man made using chemicals and oil.

Question b.
Soap and Synthetic detergents
Answer:

Soap	Synthetic detergents
1. Soap is man-made detergent, it is in use since ancient times.	1. Synthetic detergent have taken the place of soap.
2. Soap loses its cleansing property in hard water it does not give lather.	2. Synthetic detergent can be used in hard water also.
3. Soap was prepared by using animal fat and wood ash.	3. Synthetic detergent are obtained by subjecting fats, kerosene to various chemical processes.
4. Variety of soaps are available, soft soap for bathing, hard soap for washing, cleaning.	4. Variety of synthetic detergents are available – Ariel, Surf Excel, etc.

Question c.
Bath soap and Soap for washing clothes
Answer:

Bath soap	Soap for washing clothes
1. Soft soap is used for bathing.	1. Hard soap is used for washing clothes.
2. Soft soap is potassium salt is fatty acids.	2. Hard soap is sodium salt of fatty acid.
3. Soft soap dissolves more easily readily in water.	3. Hard soap do not dissolve easily in water.
4. Now a days many perfumes, moisturizes are mixed to make it more attractive and useful.	4. In this type of soap now a days germicides, anti foaming agents are mixed to make it more useful.

Question d.
Modern cement and Ancient cement
Answer:

Modem cement	Ancient cement
1. Cement manufactured from 60% lime, silica 25% and alumina 5%. the rest is iron oxide and gypsum.	1. Romans used to make aqueous cement by mixing volcanic ash in moistened lime. It was very durable.
2. It is the most commonly used cement for Construction work.	2. It is Roman cement volcanic ash prevent cracks from spreading.
3. It is called Portland Cement.	3. It is called Aqueous Cement.

4. Explain why –

Question a.
Soap cannot be used in hard water.
Answer:

Question b.
Oil does not mix in water. However, oil and water become homogenous if a sufficient quantity of detergent is added.
Answer:

Question c.
Synthetic detergents are superior to soap.
Answer:

Question d.
Often coloured spots are formed on clothes during washing.
Answer:

Question e.
Tobacco masheri should not be used for cleaning teeth.
Answer:

Project:

Question 1 Maharashtra Board Solution

Visit a cement factory. See how cement is prepared and discuss the process.

Question 2 Maharashtra Board Solution

Write a conversation based on cement houses, mud-houses and wattle-and-daub houses.

Class 7 Science Chapter 15 Materials We Use Important Questions and

Solution & Step-by-Step Answer:

Fill in the blanks:

Question 1 Maharashtra Board Solution

The principal ingredients of a toothpaste are ………………. and ………………. which remove the dirt on the teeth.