Diversity In Living Organisms — Science STD 9 — Question

Calculate the mass of 3.011 × 10²⁴ atoms of carbon.

Why is it not possible to see an atom even with the most powerful microscope?

State two factors which determine the momentum of a body.

Identify the following fishes:

1. Fish with 5 to 7 pairs of gills.
2. Fish with air bladder.

A sponge can be compressed. Is it solid or not? Why?

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.

If a fresh egg is put into a beaker filled with water, it sinks. On dissolving a lot of salt in the water, the egg begins to rise and then floats. Why?