Our Environment — Science STD 10 — Question

1. Give an example of a metal which:

1. Is a liquid at room temperature.
2. Is kept immersed in kerosene for storing.
3. Is both malleable and ductile.
4. Is the best conductor of heat.

2. Name the process of obtaining a pure metal from an impure metal through electrolysis. Suppose you have to refine copper using this process, then explain mentioning inwith the help of a labelled diagram the process of purification, brief the materials used as (i) anode, (ii) cathode and (iii) electrolyte.

Name five stimuli which act on plants. Name the type of tropism produced by each one of these stimuli.

The stem of a fruit tree X fixed in soil is cut in a slanting way. The upper part of stem of another fruit tree Y of different variety of same species is also cut in a slanting way. The cut stem of tree Y, without roots but having some leaves, is placed over the rooted cut stem of tree X in such a way that their cut surfaces fit together properly. While joining the two cut stems, care is taken to make sure that the layer Z of one cut stem is in contact with layer Z of the other cut stem. The joint of cut stem is The stem of a fruit tree X fixed in soil is cut in a slanting way. The upper part of stem of another fruit bound tightly with a piece of cloth and covered properly with polythene. Soon the cut heals and the two stems grow together and become one fruit tree producing leaves, flowers and fruits.

1. What is the name of this method of producing plants or trees?
2. What name is given to the cut stem of tree X having roots?
3. What name is given to the cut stem of tree Y which has no roots but has some leaves?
4. Name the layer Z.
5. Why should the layer Z of one cut stem be in contact with the layer Z of the other cut stem?
6. Name any four fruit trees which are usually bred by this technique.
7. State any one advantage of producing fruit trees by this technique.

Describe the process of urine formation in kidneys.

The process of ultra-filtration is essential in urine formation, where does this step occur in nephron?

1. What is an electromagnet? List any two uses.
2. Draw a labelled diagram to show how an electromagnet is made.
3. State the purpose of soft iron core used in making an electromagnet.
4. List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.

An object is placed at a distance of 10cm from a convex mirror of focal length 5cm.

1. Draw a ray-diagram showing the formation of image.
2. State two characteristics of the image formed.
3. Calculate the distance of the image from mirror.

Some sugar solution is taken in a test-tube and a little of substance X in powder form is added to it. The mouth of test - tube is closed with a cork and allowed to stand for sometime. On opening the cork, a characteristic smell of substance Y is obtained and a gas Z is also observed to be formed. The gas Z extinguishes a burning matchstick.

1. What could be X, Y and Z?
2. What is the process of converting sugar into substance Y by the action of X known as?
3. What type of respiration is exhibited by X in the above process?

The pH values of five solutions A, B, C, D and E are given below:

1. 1
2. 5
3. 7
4. 11
5. 13

Which solution is:

1. Weakly alkaline.
2. Neutral.
3. Strongly acidic.
4. Strongly alkaline, and.
5. Weakly acidic?