Chapter 13 Changes – Physical and Chemical Solutions

Maharashtra State Board Class 7 Science Solutions Chapter 13 Changes – Physical and Chemical

Class 7 Science Chapter 13 Changes – Physical and Chemical Textbook Questions and Answers

1. Distinguish between the following.

Question a.
Physical change and Chemical change
Answer:

Question b.
Periodic changes and Non-periodic change
Answer:

Question c.
Natural change and Man-made change
Answer:

2. Under which different types can the following changes be classified?

Question a.
Conversion of milk into yoghurt.
Answer:
Manmade (useful).

Question b.
Bursting of cracker.
Answer:
Manmade (fast change).

Question c.
Occurrence of an earthquake.
Answer:
Non-periodic.

Question d.
Revolution of earth around the sun.
Answer:
Periodic. (Natural change)

Question e.
Stretching of a spring.
Answer:
Physical, reversible change.

3. Give reasons.

Question a.
While purchasing canned food, its expiry date should be checked.
Answer:

Question b.
An iron article should be given a coat of paint.
Answer:

Question c.
A Wooden article should be polished.
Answer:

Question d.
Copper and brass utensils should be tinned.
Answer:

Question e.
A dry handkerchief gets wet at once on dipping in water, but it takes long for a wet handkerchief to dry.
Answer:

4. What will you take into account while identifying the following:

Question a.
A physical change in a substance.
Answer:
I will take into account the following facts.

Question b.
A chemical change in a substance.
Answer:
I will take into account the following facts.

5. Read the paragraph and note down the various types of changes it mentions.

Question a.
Read the paragraph and note down the various types of changes it mentions.
It was nearing six o’clock in the evening. The sun was setting. A breeze was blowing. Leaves on the tree were shaking. Sahil was sitting in the courtyard, rolling balls of wet soil and shaping them into various toys. Then he felt hungry and went into the house. Mother made a dough from wheat flour and fried purees. While eating hot purees, his attention was drawn outside the window. It had started raining. There was lighting too. Sahil was enjoying his dinner in the dim light.
Answer:

Project:

Question a.
Visit a place where work like powder coating. spray painting is done. Make a note of the information you obtain.

Class 7 Science Chapter13 Changes – Physical and ChemicalImportant Questions and Answers

Fill in the blanks and rewrite the sentences:

State whether the following statements are True or False. Correct and rewrite the false statement:

Define the following.

Name or Give two example of:

Match the following: