Coal and Petroleum — Science STD 8 — Question

Name the instrument (or device) which is needed to see the micro-organisms.

Name the hormone which brings about metamorphosis in silk moth and changes caterpillar (larva) into adult silk moth.

Which gas in the upper atmosphere prevents ultraviolet radiations of the sun from reaching the earth?

If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?

Which part of the eye gets affected if someone is suffering from cataract? How is it treated?

Is it possible that the decreasing amount of air in the tumbler had something to do with decreasing loudness of the ring?

Name the gland which secretes insulin hormone.

An electric spark is struck between two electrodes placed near each other in a closed tank full of petrol. Will the petrol catch fire? Explain your answer.

Name two main types of reproduction prevalent in animals.

What do the testes in a man produces?