Question

What is photosynthesis?
2. Write the names of four animals from which are get wc
3. Why does a substance expand on heating?
4. How will you test the presence of starch in leaves?
5. What is meant by galvanisation?
6. Name the processes involved in the nutrition in the anim
7. What are organic acids?
B. Write two methods to prevent iron from rusting.
2. Write four uses of bases.
. Explain neutralization reaction.​

Answer 1

• Answer:  3.Heat causes the molecules to move faster, (heat energy is converted to kinetic energy ) which means that the volume of a gas increases more than the volume of a solid or liquid. However, gases that are contained in a fixed volume cannot expand - and so increases in temperature result in increases in pressure.    

Answer 2

Answer:

(1) The process by which green plants use sunlight to make their own food from carbon dioxide and water is known as photosynthesis. This is done in the presence of chlorophyll.

(2) goat and horse

(3) temperature determines the intermolecular spacing in a substance and thus causes expansion and contraction in it.

Objects expands on heating because the intermolecular spaces are increased by applying heat energy to them. They contract on cooling as we are removing the heat energy from them.

(4) Take a leaf from the plant, decolorize it with boiling alcohol, and test the presence of food (starch) with iodine solution. The food prepared by plants (carbohydrates) through the process of photosynthesis is stored as starch. This starch reacts with the iodine solution to change to blue-black color. Only those portions of the leaf that contain starch would change to blue-black color when tested with iodine.

(5) Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting.

(6) Ingestion, digestion, absorption, assimilation and egestion are the five steps of nutrition included in animals

(7)  An organic acid is an acid that is found naturally in plants and animals. Generally, organic acids are weak acids and do not dissociate completely in water.

(8)  Rusting of iron can be prevented by:

1. Coating its surface with paint or by applying grease, oil or varnish.

2. Galvanization -

(9)   Sodium hydroxide [​NaOH]​ is used in the manufacture of soap.     Calcium hydroxide [Ca(OH)2] is used in the manufacture of bleaching powder.

(10)  Neutralization reaction is when acid reacts with base and produce salt and water.

Explanation: