Light – Reflection and Refraction — Science STD 10 — Question

Every household produces a lot of material A daily. In one of the methods of disposal B, material A is burned at a very high temperature of about 1000°C in a structure called C. During this process, the organic matter present is removed as D and E whereas F is left behind (which can be dumped in a landfill site).

1. What is material A?
2. Name the method of disposal B.
3. What is structure C known as?
4. What are (i) D (ii) E, and (iii) F?
5. This method is especially suitable for the disposal of materials produced by certain institutions. Name such institutions.

At what distance from a concave mirror of focal length 10cm should an object be placed so that:

1. Its real image is formed 20cm from the mirror?
2. Its virtual image is formed 20cm from the mirror?

Draw a neat labelled diagram of the human excretory system.

1. The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.
2. Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.
3. State Modern periodic law.

What is lens formula? Give its sign conventions and assumptions.

Arrange the following elements in the increasing order of their metallic character Mg, Ca, K, Ge, Ga.

Atomic number of a few elements are given below:
10, 20, 7, 14

1. Identify the elements.
2. Identify the Group number of these elements in the Periodic Table.
3. Identify the Periods of these elements in the Periodic Table.
4. What would be the electronic configuration for each of these elements?
5. Determine the valency of these elements.

What is meant by power of a lens? Define its S.I. unit. You have two lenses A and B of focal lengths +10cm and -10cm respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8cm from the lens? Draw a ray diagram to justify your answer.

Why should we use the exhaustible natural resources judiciously?

Explain with example how characteristics of a population changes over the years for the following situations:

1. To gain survival advantage.
2. Due to accidental survival.
3. Temporary change of characteristics.