Question

Identify the physical change from the following:

formation of clouds, mixing of iron filings and sand, formation of curd from milk, rusting of iron, melting of wax.

Answer 1

Definition: A physical change is one in which the shape, size, appearance, or state of a substance may alter, but the chemical composition remains the same.

Physical change does not involve change in composition of substance.

1. formation of clouds: The formation of clouds is physical change because there is phase transformation cycle of nature water from liquid to gas and then ,gas to liquid.
2. Mixing of iron filings and sand: Mixing of iron and sand is easily separated by using magnet.Thus, it is a physical change.
3. Rusting of iron: It happen when iron come in contact with air.Thus,it is chemical change.
4. Curd from milk: It is chemical change.
5. .Melting of wax: It is chemical change. Wax is made up of hydrocarbon which melts and becomes a gas and the hydrocarbon are broken down.

Physical change: formation of clouds, Mixing of iron filings and sand these are physical changes.