Question

E. State whether the following are physical or chemical change
1. Drying of wet clothes 2. Formation of curd from milk
Burning of wood
s. Dissolving salt in water
7. Burning of coal
8. Glowing of an electric lamp
F. Answer the following in detail.photosynthesis​

Answer 1

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First, let's know what really is physical change and a chemical change.

• Physical change - The type of change in which the physical properties or appearance of a matter is changed without a change in the chemical properties is known as physical change. It can usually be reversed.

• Chemical change - The type of change in which the chemical properties of a matter changes is known as chemical change. It usually can't be reversed.

Now, let's state whether the given following changed are physical change or chemical change -

1. Drying of wet clothes - Physical change. [Since there's no change in the chemical property, only changes in physical property.]
2. Formation of curd from milk - Chemical change. [Change in chemical properties of milk takes place and it is formed into curd.]
3. Burning of wood - Chemical change. [Since, it can't be reversed.]
4. Dissolving of salt in water - Physical change. [It can be reversed, though with difficult methods.]
5. Burning of coal - Chemical change. [It can't be reversed and there's change in chemical property.]
6. Glowing of an electric lamp - Physical change. [It can be reversed, there's no change in chemical property.]

Explain about Photosynthesis.

• The process by which green plants make food from a green pigment called chlorophyll, with the help of sunlight and carbon dioxide is known as photosynthesis.

• During the process, light energy is captured and used to convert water, minerals, carbon dioxide into chemical energy.

Answer 2

Physical change -

• The type of change in which the physical properties or appearance of a matter is changed without a change in the chemical properties is known as physical change. It can usually be reversed.
• Chemical change - The type of change in which the chemical properties of a matter changes is known as chemical change. It usually can't be reversed.

Now, let's state whether the given following changed are physical change or chemical change -

• Drying of wet clothes - Physical change. [Since there's no change in the chemical property, only changes in physical property.]
• Formation of curd from milk - Chemical change. [Change in chemical properties of milk takes place and it is formed into curd.]
• Burning of wood - Chemical change. [Since, it can't be reversed.]
• Dissolving of salt in water - Physical change. [It can be reversed, though with difficult methods.]
• Burning of coal - Chemical change. [It can't be reversed and there's change in chemical property.]
• Glowing of an electric lamp - Physical change. [It can be reversed, there's no change in chemical property.]

Explain about Photosynthesis.

• The process by which green plants make food from a green pigment called chlorophyll, with the help of sunlight and carbon dioxide is known as photosynthesis.
• During the process, light energy is captured and used to convert water, minerals, carbon dioxide into chemical energy.