The Fundamental Unit of Life — Science STD 9 — Question

Which object is vibrating when the following sounds are produced?

1. The sound of a sitar.
2. The sound of table.
3. The sound of a tuning fork.
4. The buzzing of a bee or mosquito.
5. The sound of a flute.

If the relative density of a substance is 7.1, what will be its density in SI units?

1. Identify the above figure.
2. Label X and Y.
3. What is the function of X?

Classify the following as physical or chemical changes:

1. Cooking of food.
2. Boiling of water.
3. Cutting of trees.
4. Dissolving salt in water.
5. Digestion of food.
6. Melting of ice.

Ice at 0°C is more effective in cooling than water at 0°C. Give reason.

A car weight 20000N climbs up a hill at a steady speed of 8 m/s, gaining a height of 120m in 100s. Calculate:

1. Work done by the car.
2. Power of engine of car.

The substance X normally exists in a physical state which can flow easily but does not fill its vessel completely. It also turns anhydrous copper sulphate blue. When substance X is cooled excessively, it changes into a substance Y which has a fixed shape as well as a fixed volume. If, however, the substance X is heated strongly, it changes into a substance Z which has neither a fixed shape nor a fixed volume.

1. Name the substances (i) X (ii) Y and (iii) Z.
2. What is the process of conversion of X into Y known as?
3. At which temperature X gets converted into Y?
4. What is the process of conversion of X into Z known as?
5. At which temperature X gets converted into Z?

What is the difference between the density and relative density of a substance?

How will you separate a mixture of iron filings and powdered carbon?

What is the difference between speed and velocity?