Combustion and Flame — Science STD 8 — Question

Seeing a crowd of students in one corner of the school, the principal rushed to see the matter and found some children beating and chasing a small lizard. On seeing the principal, all children fled to their classes except Alok who requested the principal to arrange for some medical assistance for the Injured animal. The principal rewarded him for his attitude.
(i) Species of few animals are very less in number. What are these species known as ?
(ii) It is wrong to harm the animals. Give reason.
(iii) Give example of some endemic species of India.

Why are lubricants (oil or grease) applied to rubbing surfaces of machines?

Consider the following materials: Copper, Sulphur, Phosphorus, Carbon (such as: pencil lead), Gold, Silver Which of these materials are: Malleable and ductile; and brittle.

Explain how, burning of fuels such as coal, petrol and diesel leads to acid rain. How is acid rain harmful?

Explain, why magnetic force is said to be a non-contact force.

Sakshi and her mother reached a jewellery shop to purchase some ornaments. She liked a bangle set very much but her mother asked not to purchase that because that was not a real gold. She asked the shopkeeper about it. The shopkeeper explained the process of gold plating, this process is also known as electroplating.
(i) Name some other materials which are used for electroplating.
(ii) What is the need of electroplating in the above case? Give one more use of electroplating.

What will be the number of images formed when an object is placed between two parallel plane mirrors facing each other?

What are the advantages of sowing seeds with a seed drill?

How do emotions like stress or worry affect us and make us sick?