English Medium Class 9 - CBSE Question Bank Solutions for Science

Note is a sound

A key of a mechanical piano struck gently and then struck again but much harder this time. In the second case

An earthquake produces which kind of sound before the mainshock wave begins

The sound produced by a thunderstorm is heard 10 s after the lightning is seen. Calculate the approximate distance of the thunder cloud. (Given the speed of sound = 340 m s^–1.)

Why is the ceiling and wall behind the stage of good conference halls or concert halls made curved?

Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound. Mark the position of compression and rarefaction on this curve. Also, define wavelengths and time periods using this curve.

If there were no atmosphere around the earth, the temperature of the earth will

One of the following factors does not lead to soil formation in nature

The growth of Lichens on barren rocks is followed by the growth of

Why do people love to fly kites near the seashore?

Why are root nodules useful for plants?

Which one is an oil yielding plant among the following?

Why is excess use of fertilizers detrimental to the environment?

Growing wheat and groundnut on the same field is called ______.

Planting soybean and maize in alternate rows in the same field is called ______.

Growing different crops on a piece of land in pre-planned succession is known as ______.

Define the terms hybridization and photoperiod.

Photoperiod affect the ______.

Define Vermicompost

Define Green manure