Structure of the Atom — Science STD 9 — Question

Wind causes weathering of rocks through:

1. Chemical change.
2. Abrasion.
3. Mechanical force.
4. Frost action.

Organisms having bigger size and have a complex structure are called as:

The number of Al³⁺ ions in 0.051g of aluminium oxide are (Atomic mass of Al = 27u, O = 16u).

________ is the characteristic of a musical sound by a which a loud sound can be distinguished from a faint sound even though both have the same pitch:

Choose the wrong statement:

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

The cell wall of meristematic cell is made of:

Rinku and Pinku had half day schools during summer. They used to go to school by autorickshaw. They observed that the auto driver covered the top of the vehicle by some mats and sprinkled water on them regularly, which keeps it cool. Which of the following phenomena is involved here:

If a particle moves in a circle with constant speed, its velocity:

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.