Which of the following does not involve a chemical reaction?
Which of the following does not involve a chemical reaction?
The correct option is D melting of candle wax on heating
Explanation for the correct option: (d) melting of candle wax on heating
When a candle wax starts to melt on heating, it is not a chemical change, but a physical change. This is because, during the process of melting, no chemical reaction is taking place. The wax is simply changing it's form and shape. The molten wax can again be shaped into a candle. So the change is temporary and reversible, unlike a chemical reaction which is permanent and irreversible change.
Explanation for the incorrect options: (a) digestion of food in our body: The nutrients present in our food undergo chemical reactions in our stomach to release simpler substances.
(b) process of respiration: The oxygen we inhale reacts with glucose in our body to release carbon dioxide and water.
(c) burning of candle wax when heated: Burning involves an oxidation reaction, in which heat and light are evolved along with the formation of water and carbon dioxide.
Hence, option(d) is the correct option.
melting of candle wax on heating
Explanation for the correct option: (d) melting of candle wax on heating
When a candle wax starts to melt on heating, it is not a chemical change, but a physical change. This is because, during the process of melting, no chemical reaction is taking place. The wax is simply changing it's form and shape. The molten wax can again be shaped into a candle. So the change is temporary and reversible, unlike a chemical reaction which is permanent and irreversible change.
Explanation for the incorrect options: (a) digestion of food in our body: The nutrients present in our food undergo chemical reactions in our stomach to release simpler substances.
(b) process of respiration: The oxygen we inhale reacts with glucose in our body to release carbon dioxide and water.
(c) burning of candle wax when heated: Burning involves an oxidation reaction, in which heat and light are evolved along with the formation of water and carbon dioxide.
Hence, option(d) is the correct option.
