G. Give reasons for the following. 1. Burning may or may not be a desirable change. 2. Boiling of water is a physical change but boiling of egg is a chemical change. 3. Clothes take time in drying during rainy season. 4, Fermentation may or may not be a desirable change. 5. Respiration is a chernical change.
Answers
Answer:
Explanation:
1. Desirable changes sometimes become undesirable changes. For example : Cooking of food require burning of wood is a desirable change . But burning of wood in forest fires is an undesirable change.
2. Boiling of egg a chemical change. In case of boiling egg the composition of egg is irreversible. New substance is formed so it irreversible. Boiling of water to form water vapors is a physical change. There is only a change in state of matter but no chemical changes has occurred.
3. Wet clothes take longer time to dry on a humid day because the air has a lot of water vapors and so it can't accommodate the water vapors created by the wet clothes. So, the water remains, in the clothes for a longer time.
4. fermentation may not be the desirable change . In the case of making curd ,the milk is fermented which is our desirable change. But when sometimes the milk becomes sour, which is due to bacteria and this is not a desirable change that we want.
5.Yes, respiration is a chemical change. Oxygen is taken during the respiration, the output should be also the oxygen in order to make it a physical change. That's why it is considered as a chemical reaction where the initial compound is oxygen and final compound is carbon dioxide