CBSE NCERT Solutions for Class 7 Science Chapter 6

NCERT solutions for class 7 science chapter 6 Physical and Chemical Changes is provided here. Students who want to score good marks in class 7 examinations should solve the NCERT questions provided at the end of each chapter.

CBSE NCERT Solutions for Class 7 Science Chapter 6:

Question-1:

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

Solution:

(a) Photosynthesis → Chemical change
(b) Dissolving sugar in water → Physical change
(c) Burning of coal → Chemical change
(d) Melting of wax → Physical change
(e) Beating aluminium to make aluminium foil → Physical change
(f) Digestion of food → Chemical change

Question-2:

State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change. (True/False)
(b) Formation of manure from leaves is a physical change. (True/False)
(c) Iron pipes coated with zinc do not get rusted easily. (True/False)
(d) Iron and rust are the same substances. (True/False)
(e) Condensation of steam is not a chemical change. (True/False)

Solution:

(a) False cutting a log of wood into pieces is a physical change.
(b) False Formation of manure from leaves is a chemical change.
(c) True
(d) False Iron and rust are different substances. Rust is oxide of iron (Fe2O3)
(e) True

Question-3:

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.

Solution:

When a candle burns, both physical and chemical changes take place. The melting
wax is physical change as there is no formation of new product. The burning of wax is chemical change as light is lit up by consuming the energy from wax. Cooking of food is both physical and chemical because raw vegetables get cooked which is a chemical change and the water changes into steam which is a physical change