Question

when a candle burns both physical amd 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 1

Answer:

When a candle burns, both physical and chemical changes take place. The melting of wax from the heat of the flame is a physical change as it does not produce new substances and it can be reversed by reversing the conditions (cooling the molten wax). On the other hand, the burning of wax is a chemical change as it produces new substances (water vapour and carbon dioxide) and it cannot be reversed by reversing the conditions. The burning of wood is another example of physical and chemical changes taking place simultaneously as the moisture present in the wood is evaporated while wood is burnt (physical change) while the actual burning of the wood produces carbon dioxide and ash (chemical change).

Answer 2

Answer:

When a candle burns, both physical and chemical changes occur:

(i) Physical change: melting of wax, vapourisation of melted wax.

(ii) Chemical change: Burning of a wick and vapours of wax to give carbon

dioxide, heat and light.

I)LPG is an other example in which physical change occurs when LPG comes out of cylinder and is converted from liquid to gaseous state and a chemical change occurs when gas burns in air.

ii)Chewing of food is a physical change as it converts food into small pieces and digestion of food is chemical change as it forms new substances after the digestion