Life Processes — Science STD 10 — Question

For what purpose (any one) were the dams constructed? Do you think dams are serving their purpose completely?

What is an olfactory indicator? Name two olfactory indicators. What is the effect of adding sodium hydroxide solution to these olfactory indicators?

How do unicellular organisms perform excretion?

What is the position of the image when an object is placed at a distance of 20cm from a concave mirror of focal length 20cm?

Name the type of reaction for the following:
Burning of natural gas.

What happens to a beam of white light when it gets refracted through glass prism? Which colour deviates the most and the least after refraction through a prism? What is likely to happen if a second identical prism is placed in an inverted position with respect to the first prism. Justify your answer.

Describe an activity to show that while paper is biodegradable but plastic (say, polythene) is non-biodegradable.

How has the traditional use of wind and water energy been modified for our convenience?

Which of the following elements would yield:

1. An acidic oxide.
2. A basic oxide.
3. A neutral oxide.

Na, S, C, K, H

Write the balanced chemical equations for the following reactions.

1. Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
2. Zinc + Silver nitrate → Zinc nitrate + Silver
3. Aluminium + Copper chloride → Aluminium chloride + Copper
4. Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride