Sound — Science STD 9 — Question

Draw labelled diagrams to represent sound of (a) low pitch, and (b) high pitch, of the same loudness.

A student placed a gas jar containing air in the upside down position over a gas jar full of red-brown bromine vapours. He observed that the red brown colour spread upwards into the jar containing air. Based on this observation, the student concluded that it is only the bromine vapour which moves up and diffuses into air in the upper jar, the air from the upper jar does not move down by diffusion into the lower jar containing bromine vapours. Do you agree with this conclusion of the student? Give reason for your answer.

The audible range of frequencies of an average human ear is from 20Hz to 20kHz. Calculate the corresponding wavelengths. (Speed of sound in air is 344ms^-1).

What is a proton? State its relative mass and charge.

What is the location of following in the cell:

1. Chromatin.
2. Chromosome.
3. Tonoplast.
4. Nucleolus.

Does the force of gravitation exist at all the places of the universe?