Question

1.Match the Column I with Column II.

Column 1	Column 2
No new substance is formed.	Irreversible change
Physical change	Reversible change
A new substance is formed.	Sawing of piece of wood
Chemical change	Melting of ice cream
Need heating	Ripening of mango.

Answer 1

(a) No new substance is formed – (ii) Reversible change

• A change which can be reversed back and will not form any new substance is called a reversible change.

(b) Physical change – (iii) Sawing of piece of wood

• Sawing of wood is a physical change because the chemical composition of wood will remain the same after cutting.

(c) A new substance is formed. – (i) Irreversible change

• A change which cannot be reversed back and will form a new substance is called an irreversible change.

(d) Chemical change – (v) Ripening of mango

• The pigment in the skin of the fruit changes during the ripening process, and this cannot be restored. Ripening of fruits is a chemical change.

(e) Need heating – (iv) Melting of ice cream

• Ice cream melts when heat is provided to it. Melting of a substance is done by heating.

Hence, the correct matches are listed below:

Column I	Column II
(a) No new substance is formed	(ii) Reversible change
(b) Physical change	(iii) Sawing of piece of wood
(c) A new substance is formed	(i) Irreversible change
(d) Chemical change	(v) Ripening of mango
(e) Need heating	(iv) Melting of ice cream