NCERT Solution
Class 7
Science
Physical and Chemical Changes
when a candle burns both physical and chemical ch...

Question:
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

Answer:

When a candle burns both physical and chemical changes takes place. When a candle is burnt, melting of wax occurs; this is a physical change. And, the burning of wax shows the chemical change.

Digestion of food is the familiar process which shows both chemical and physical changes. In starting, breaking down of large food particles into the smaller ones shows the physical change. The process of digestion of food is a chemical change in which many new substances are formed.

1
0
0
Report?

Report a problem on Specifications:

Email id:

Comments

< Previous Question

Next Question >

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='11' AND subId='16' AND ex_no!=0 AND status=1 and id!=5999 ORDER BY views desc, last_viewed_on desc limit 0,10

Popular questions of class 7 Science

Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food

Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth

Sketch the cross section of soil and label the various layers.

Here is a crossword puzzle: Good luck!

Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body

Down
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water

Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO₂?

Sketch the reproductive parts of a flower.

Solve the following crossword puzzle with the clues given:

Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.

Describe how crystals of copper sulphate are prepared.

Write one similarity and one difference between the nutrition in amoeba and human beings.

Why does an athlete breathe faster and deeper than usual after finishing the race?

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='11' AND subId='16' AND ex_no!=0 AND status=1 and id!=5999 ORDER BY last_viewed_on desc limit 0,10

Recently Viewed Questions of Class 7 Science

Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Sepals

What are decomposers? Name any two of them. What do they do in the forest?

Fill the missing word in the blank spaces in the following statements:

(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———.

In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

Mark ëTí if the statement is true and ëFí if it is false:

(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)

When are the maximum and minimum temperatures likely to occur during the day?

Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Fill in the blanks:

(a) An image that cannot be obtained on a screen is called ____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen.

Question:
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

< Previous Question

Next Question >

Popular questions of class 7 Science

Recently Viewed Questions of Class 7 Science

Comments

Comment(s) on this Question

NCERT Solutions

Quick Links

Resources

Support

Question: When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

< Previous Question

Next Question >

Popular questions of class 7 Science

Recently Viewed Questions of Class 7 Science

Comments

Comment(s) on this Question

NCERT Solutions

Quick Links

Resources

Support

Question:
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.