The Fundamental Unit of Life — Science STD 9 — Question

How will you separate common salt, sand and iron filings from their mixture?

Describe the method of separating a mixture containing common salt, sand and ammonium chloride.

What is the difference between a compression and a rarefaction in a sound wave? Illustrate your answer with a sketch.

The figure shows an x-t graph of a particle moving along a straight line. What is the sign of the acceleration during the intervals OA, AB, BC, and CD?

Explain the various methods of crop improvement. Name one improved variety of Rice, Maize, Soybean, Sunflower and Mustard.

There is a large group of materials P which can be divided into three groups Q, R, and S on the basis of their properties. The substances belonging to group Q can be solids, liquids or gases. The solids belonging to group Q are usually electrical insulators. Most of the substances of group R are solids which are good conductors of electricity. The substances belonging to group S are neither insulators like Q nor good conductors like R. The properties of S are intermediate between those of Q and R.

1. What could the group of materials P be?
2. Name the substances Q. Give two examples of such substances.
3. Name the substances R. Write two examples of such substances.
4. Name the substances S. Give two examples of such substances.
5. Out of Q, R and S, which substances are malleable and ductile?

Give two examples each of longitudinal waves and transverse waves.

Describe the Rutherford’s model of an atom. State one drawback of Rutherford’s model of the atom.