Atoms and Molecules — Science STD 9 — Question

A particle is moving in a circular path of radius r. The displacement after half a circle would be:

While preparing a slide for observing onion peel under a microscope, the onion peel is immediately kept in a watch-glass containing a drop of water. Why this is done?

Sound waves travel fastest in:

Why do we not hear the screams of a bat:

Which of the following element is represented by the chemical symbol P:

The upward force exerted by a liquid on an object is called _______?

A passenger in a moving train tosses a coin which falls behind him. This shows that the motion of train is:

Tendon is a structure which connects _________.

An echo-sounder in a trawler (fishing boat) receives an echo from a shoal of fish 0.4s after it was sent. If the speed of sound in water is 1500m/s, how deep is the shoal?

‘Note’ os a sound:

1. Of a mixture of several frequencies.
2. Of mixture of only two frequencies.
3. Of a single frequency.
4. Always unpleasant to listen to.