Electric Current and its Effects — Science STD 7 — Question

One day Sachin had gone to his uncle who lives in a village. He saw there a large number of people defecate in an open area because proper toilet facilities are not there. He wondered about the groundwater contamination, as he studied in his class that this act may cause water-borne diseases. He convinced village people to make toilets to avoid such an out break of water-borne diseases.

1. Name two water-borne diseases.
2. Explain vermi-composting toilets.
3. What values are shown by Sachin?

Make simple pendulums of different length and note their time periods and state the relation between length and time period of it.

Give two uses of the following acids.

1. Nitric acid.
2. Hydrochloric acid.
3. Sulphuric acid.

Draw a diagram of the solar and lunar eclipse and write down about the
(i) total solar eclipse
(ii) partial solar eclipse
(iii) total lunar eclipse
(iv) partial lunar eclipse

Rohan went to the desert of Rajasthan with his freinds. He saw an animal. It had a hump. Its feet had large soles. He wondered about this animal. He found that these were adaptations of that animal which helped it to survive in very hot and dry climate of the desert.
Answer the following Questions on the basis of the observations seen by Rohan.

1. Name the animal Rohan observed in the desert of Rajasthan?
2. What role does this hump has in this animal?
3. Why do it has large soles?
4. Can you give same more adaptations of this animal which help it to survive in desert?
5. What values do you observe in Rohan?

Design an activity to show the soil erosion on a barren land.

Compare images formed by a pinhole camera and a plane mirror.

What is lightning?

Why is transport of materials necessary in a plant or in an animal? Explain.