Question

Short answer type questions
11) When a copper vessel is exposed to moist air for long, it acquires a dull green coating
Explain this reaction using a suitable chemical equation
12) Explain 5 R principle using some environment friendly habits for reducing environment
pollution
13) Comment upon certain advantages of Manure.
14) Explain some commercial as well medicinal uses of microorganisms
15) Give reason
(a) Copper cannot displace zinc from its salt solution
(b) Sodium and potassium are stored in kerosene.
16) Why phosphorus is stored in water?
177 Explain displacement reaction using suitable example.
18) Explain the difference between thermoplastic and thermosetting plastics
19) Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from
synthetic material Advise Rana, giving your reason
20) What is pasteurization? Write it's application

I will mark as brainlist if you give me right answer of these questions of class8th science​

Answer 1

Answer:

11)When a copper vessel is exposed to moist air for long time acquires a dull green colour which is form due to the formation of basic carbonate due to its reaction with CO2 Present in the air

12)According to the 5 R's, four actions should be taken, if possible, prior to 'recycling': refuse, reduce, reuse, repurpose, and then recycle. Incorporating this methodology into your business' waste reduction and recycling efforts will minimize landfill waste and help take your recycling program to the next level.

13)It increases the water holding capacity of the soil. ... They are quick in providing plant nutrients and restoring soil fertility. They are portable and easy to transport.

Answer 2

Answer:

Question. Comment upon the certain Advantages of manure.

Ans.

1. These are good source of micronutrients
2. Improve soil fertility
3. Cost effective
4. Reduces soil erosion and leaching
5. It can be transported easily
6. Improve the physical properties of soil

Question. Sodium and potassium are stored in kerosene.

Ans. Sodium and Potassium are highly reactive metals and react with the oxygen, corbon dioxide and moisture present in the air such that it may even cause a fire.

Question. Explain Displacement reaction using suitable example.

Ans. A displacement reaction is the one wherein a atom or a set of atoms is displaced by another atom in the molecules.

Example. On mixing a barium cloride with magnesium sulfate.

Question. Copper cannot displace zinc from its salt solution.

Ans. Metals are the good conductor of heat and electricity. Copper is less reactive than zinc. Therefore Copper cannot displace zinc from its salt solution.

Question. Why phosphorus is stored in water?

Ans. Phosphorus is highly reactive , it is usually stored under water, to prevent exposure to the air. It is also extremely toxic, even in very small quantities.

Question. Explain the difference between thermoplastic and thermosetting.

Ans. Thermoplastic can be synthesized with the process called the addition polymerization.

Thermosetting plastics can be synthesized with the process called the condensation polymerization.

Question. What is pasteurization? Give its application.

Ans. Pasteurization is widely used in the dairy industry and other food processing industries to achieve food preservation and food safety. Most liquid products are heat treated in a continuous system where heat can be applied using a plate heat exchanger or the direct and indirect use of hot water and steam.

I hope it will help you.

I know much..

Please mark me as a brainlist...