Substances in Common Use — Science STD 9 — Question

Chapattis made from wheat only swell up but bread becomes spongy, soft and easy to digest. Why is it so?

What problem do you have on painting the house and furniture?

How is yoghurt made from milk? What exactly happens in this process?

(a) Can your father climb stairs as fast as you can?
(b) Will you fill the overhead water tank with the help of a bucket or an electrical motor?
(c) Suppose Raj ashree, Yash and Ranjeet have to reach the top of a small hill. Raj ashree went by car. Yash went cycling while Ranjeet went walking. If all of them choose the same path, who will reach first and who will reach last? (Think before you answer.

A person standing near a hill fires a gun and hears the echo after 1 second. If speed of sound in air is 340 m/s. Find the distance between the hill and the person.

Explain, how ‘Jaipur Foot’ has transformed the lives of the disabled in India?

Write the chemical formula Bleaching powder, common salt, baking soda, washing soda

What should be the dimensions and the shape of classrooms so that no echo can be produced there?

Genetic engineering

Make a list of elements in the monoatomic and in the diatomic molecular state. (Make a list and discuss;