Photosynthesis is a natural process by which green plants manufacture food in the presence of sunlight.

(a) Are any new products formed during the above process?

(b) Can the change be reversed or is irreversible?

(c) State the conclusions which can be drawn, to represent photosynthesis as a physical or a chemical change.

Give reasons why - separation of mixtures e.g., iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.

Fill in the blanks with the appropriate words for each of the statements given below:

1. Germination of seeds is considered a …………… [physical/chemical] change.

2. If a change is permanent and irreversible, it is considered a …………… [chemical/physical] change.

3. Heating a piece of iron is considered a …………… [physical/chemical] change, while heating a piece of coal [carbon] is considered a …………… [physical/chemical] change.

4. Chemical changes may involve exchange of energy in the form of …………… & …………… [light/sound/magnetic /heat].

5. Change of milk to curd is a …………… [desirable/undesirable] change.

State whether the following statements are true or false. If false, write- the correct statement.

1. Desirable changes are meaningful, while undesirable changes are unfavorable.

2. During physical changes, the composition of the original substance is not altered, but the properties of the original substance are altered.

3. During a chemical change the composition of the original substance is not altered, and the change is irreversible.

4. Melting of butter and wax are examples of chemical changes.

5. The melting of ice is an exothermic, irreversible chemical change.