Tissues — Science STD 9 — Question

In which of the following conditions, the distance between the molecules of hydrogen gas would increase?

1. Increasing pressure on hydrogen contained in a closed container.
2. Some hydrogen gas leaking out of the container.
3. Increasing the volume of the container of hydrogen gas.
4. Adding more hydrogen gas to the container without increasing the volume of the container.

Why does perspiration leave a cooling effect on our body:

Parenchyma which contains chlorophyll is called:

When a gas jar full of air is placed upside down on a gas jar full of bromine vapours, the red-brown vapours of bromine from the lower jar go upward into the jar containing air. In this experiment:

1. Air is heavier than bromine.
2. Both air and bromine have the same density.
3. Bromine is heavier than air.
4. Bromine cannot be heavier than air because it is going upwards against gravity.

Which one of the following statements about power stations is not true?

1. Hydroelectric power stations use water to drive turbines.
2. In a power station, turbines drive generators.
3. Electricity from thermal power stations differs from that produced in hydroelectric power stations.
4. In hydroelectric power stations and thermal power stations, alternators produce electricity.

Define velocity.State its unit:

Nereis and Leech belongs to:

What is the central role of nucleus?