Light — Science STD 8 — Question

Arrange the following fibres in the order of increasing strength (keeping the fibre of least strength first):
Nylon, Cotton, Wool, Polyester, Silk.

Whenever we push a very heavy box kept on the ground, it does not move at all because frictional force balances the force that we apply. So, there is no net movement of this box. It acts in a direction opposite to the force we apply.

What are rods and cones in the retina of an eye?

In which part of the sky can you find Venus if it is visible as an Evening Star?

If you see a person whose clothes are on fire, how will you extinguish the fire? Give reason for your answer.

Name three useful products of coal.

How can you reduce the drag on something moving through the air?

A student lists the following agricultural practices for crop production: Irrigation; Removal of weeds; Preparation of soil; Storage of food grains; Sowing; Adding manure and fertilisers.
Which agricultural practice is missing from the above list?

Does pure water conduct electricity? If not, what can we do to make it conducting?

Explain why, distilled water does not conduct electricity but tap water conducts some electricity.