Class 7 Physical and Chemical Changes Important Questions for exams

Class 7 Physical and Chemical Changes Important Questions for exams. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

PHYSICAL AND CHEMICAL CHANGES

1. Difference between physical and chemical changes Physical change Chemical change

2. The properties such as __________, __________, _________ and ____________ of a substance are called its physical properties.

3. During a chemical change / reaction, when new products are formed, it is usually accompanied by

(a) Release or absorption of energy in the form of heat, light, etc

(b) Production of sound

(c) Change in smell

(d) Change in color

(e) Formation of gas

4. Classify the following changes into physical and chemical changes:       

Rusting- Rusting is the process in which iron reacts with oxygen and moisture in the air to form a reddish brown coating on its surface of a substance called rust. Presence of common salt speeds uprusting. If either oxygen or moisture is absent, rusting does not occur. Conditions required for rusting to take place:-

Presence of ______________

Presence of ______________

Rusting is faster when content of ______________ is high in air.
Rusting can be prevented by

Applying a coat of paint or _____________

Depositing a layer of a metal like _______________ or __________ on iron.

Why do ships suffer a lot of damage from rusting?

In spite of ships being painted, they suffer a lot of damage because a part of the ship is always in water and water droplets cling on the part which is above water.

Ships sail in sea and sea water contain salts. Salt make rusting faster.

Galvanisation – It is the process of depositing a layer of molten zinc on iron

Practice exercise

Physical and chemical changes

Q.1. Fill in the blanks:-

a) ___________reactions are accompanied by other absorption or evolution of energy.

b) Matter can be classified as ___________, __________and ________.

c) New substances are formed in a _________reaction.

d) A change in physical state of a substance is called ____________change.

Q.2. Complete the following table giving reasons, whether the classification in column B is correct or

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