1. Write any two functions of organic fertilizer.
2. Any two functions of organic fertilizer are:
   1. Plants grow well and bear good fruit.
   2. They retain the water in the soil and also prevent the soil damage.
3. Write two reasons that compost fertilizer is better than chemical fertilizer.
4. Compost fertilizer is better than chemical fertilizer because of the following points:
   1. It retains the water in the soil.
   2. It does not change the texture of the soil.
5. Mention any two reasons of chemical pollution.
6. Any two reasons of chemical pollution are:
   1. Excessive use of chemical fertilizers.
   2. Use of synthetic cleanser.
7. Write two difference between thermo-plastic and thermo-setting plastic.
8. Difference between thermo-plastic and thermo-setting plastic are shown below in table:

   Thermo-plastic	Thermo-setting plastic
   It becomes soft on heating.	It does not become soft on heating.
   It is elastic and less brittle.	It is non-elastic and more brittle.
   It can be turned into desired shapes.	It cannot be reshaped and reused.

9. Define with two points that 'detergent is more useful than soap.'
10. Two points that defines detergent is more useful than soap are:
    1. Detergent is soluble in both soft and hard water but soap is soluble only in soft water.
    2. Detergent has more capacity to remove dust than soap.
11. Write any two reasons of high use of plastic.
12. Reasons of high use of plastic are listed below:
    1. It does not corrode and is stainless.
    2. It has a long lifespan.
    3. It is do not get rot, rust. It is cheap and light.
13. Why is gypsum added to cement? Write any two measures to control chemical pollutions.
14. Gypsum is added to cement because it increases the setting time of the cement and improve its quality.
    The measures to control chemical pollutions are listed below:
    1. Public awareness should be raised.
    2. Population growth and unplanned urbanization should be controlled.
15. Detergent is more useful than soap, why?
16. Detergent is more useful than soap because it has better cleansing and wetting property than soap. It is more soluble than soap and can produce lather even with hard water.
17. Write any two differences between soap and detergent.
18. The differences between soap and detergent are shown below in table:

    Soap	Detergent
    Sodium or potassium salt of fatty acid is called soap.	The synthetic petrochemical that has better cleansing property than soap is called detergent.
    It is less soluble in water than detergent.	It is more soluble in water than soap.
    It has relatively weak cleansing action.	It has relatively strong cleansing action.
    It is biodegradable in nature and does not cause pollution.	It is non-biodegradable in nature and causes pollution.
    For example: Sodium palmitate, Sodium oliate, etc.	For example: Sodium pyrophosphate, alkyl benzene sulphonate, etc.

19. Why bakelite is called thermosetting plastic?
20. Bakelite is called thermosetting plastic because they are hard and strong and are resistant to heat, they cannot be moulded again and again.
21. Why bakelite is used instead of PVC to make the handle of pressure cooker?
22. PVC is thermoplastics, it softened on heating but bakelite is hard and brittle. Its monomers are arranged in cross linkage, which cannot be broken down by heating. So, to handle the heat produced by the handle of pressure cooker bakelite is used instead of PVC.
23. Write any one benefit of adding lead monoxide while making ordinary glass.
24. Adding lead monoxide increases the refractive index while making ordinary glass.
25. Write any two differences between bakelite and polythene.
26. Any two differences between bakelite and polythene is shown below in table:

    Bakelite	Polythene
    It thermosetting plastics.	It thermoplastics.
    It is used in cooking pan handles, plugs, switches, etc.	It is used to carry stuffs.

27. Why are plastics considered as the major cause of chemical pollution? Give two reason.
28. Plastics are considered as the major cause of chemical pollution because of the following reason:
    1. It is non-biodegradable in nature.
    2. It produce poisonous gases and smoke when burnt.
29. Write any two difference between bakelite and PVC.
30. Any two differences between bakelite and PVC is shown below in table:

    Bakelite	PVC
    It thermosetting plastics.	It thermoplastics.
    It is used in cooking pan handles, plugs, switches, etc.	It is used in the building and construction.

31. Potassium is needed for the plant, why? Give the name of one chemical fertilizer which supplies potassium to the soil.
32. Potassium is needed for the plant because in photosynthesis, potassium regulates the opening and closing of stomata, and therefore regulates CO₂ uptake. Potassium sulfate is the name of chemical fertilizer which supplies potassium to the soil.
33. By which properties of ceramics, it is used to make utensils for keeping food materials?
34. Ceramics can withstand high temperature. It is resistant to chemicals, poor conductors of heat and electricity and is hard and brittle. So, it is used to make utensils for keeping food materials.
35. Electric switch and handle of pressure cooker are made up of Bakelite, why?
36. Electric switch and handle of pressure cooker are made up of Bakelite because it is hard and brittle. Its monomers are arranged in cross linkage, which cannot be broken down by heating.
37. Water used for washing clothes with detergent is not useful for the plants, why?
38. Water containing detergent damage to the soil structure by raising the alkalinity of soil. Consequently, the damaged soil deteriorates healthy plants. So, water used for washing clothes with detergent is not useful for the plants.
39. Why is quartz glass used to make electrical appliance and laboratory apparatus?
40. Quartz glass does not contain other ingredients except silica. It is superior to other types of glasses due to its purity. It has a very low coefficient of thermal expansion. So, it is used to make electrical appliances and laboratory apparatus.