Question

1. Mention some useful and some harmful changes around you
2. Define desirable and undesirable changes.
3. Write three differences between physical changes and chemical changes.
4. Write one instance in which both physical as well as chemical changes take place simultaneously
5. How is making a sugar solution a reversible change?​

Answer 1

Answer:

Reversible changes and Irreversible changes

All changes in the world are one of the two types – Reversible changes and irreversible changes. A change which can happen backward, that is, can be reversed is called a reversible change. If you keep water in the freezer for some time, it transforms into ice. But as soon as you take it out of the freezer, it turns into water again. This is a reversible change. Similarly, if you boil water, it evaporates and becomes water vapor. When you cool this vapor down, it turns back to water.