4. What type of change is burning of fossil fuel
1) Reversible change
2) Irreversible change
3) Physical change
4) Slow change
Answers
Answer:
Option 2 is correct answer
Answer:
(a) The molecules of the substances do not change.
Physical changes are reversible, the molecules of the substance remain exactly the same before and after the physical change.
(b) a chemical change
Growth occurs due to the intake of food. The substances present in food are used to nourish the cells and allow them to grow/divide. Hence, growth is a chemical change in which the molecules present in the food undergo changes to form molecules that enhance growth.
(c) either a physical change or a chemical change, depending on the conditions.
When two substances are mixed together, it can result either in a physical or chemical change. This depends on the substances that are mixed and also on the conditions
(a) always irreversible.
Chemical reactions always result in forming new substances with different molecules. It is not easy to get back the original substances. Hence, the chemical changes are permanent and irreversible