Management of Natural Resources — Science STD 10 — Question

Find the position and size of the virtual image formed when an object 2cm tall is placed 20cm from:

1. A diverging lens of focal length 40cm.
2. A converging lens of focal length 40cm.

Which gas is usually liberated when an acid reacts with a metal? How will you test for the presence of this gas?

What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.

Distinguish between resistance and resistivity.

Construction of a dam on a river often results in the reduction of fish catch. Why is it so?

Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and how it is corrected by a lens.

Explain with the help of a labelled ray diagram, why a pencil partly immersed in water appears to be bent at the water surface. State whether the bending of pencil will increase or decrease if water is replaced by another liquid which is optically more dense than water. Give reason for your answer.

What is meant by human circulatory system? Name the organs of the circulatory system in humans.

In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.

What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.