Periodic Classification of Elements — Science STD 10 — Question

An electric heater is connected to the 230V mains supply. A current of 8A flows through the heater.

1. How much charge flows around the circuit each second?
2. How much energy is transferred to the heater each second?

1. Draw a diagram to show the formation of image of a distant object by a myopic eye. How can such an eye defect be remedied?
2. State two reasons due to which this eye defect may be caused.
3. A person with a myopic eye cannot see objects beyond a distance of 1.5 m. What would be the power of the corrective lens used to restore proper vision?

An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.

State some of the uses of mineral acids in industry.

Find the equivalent resistance across the two ends A and B of the following circuit.

Give two examples each of:

1. Group 1 elements.
2. Group 17 elements.
3. Group 18 elements.

a. Draw a diagram of human alimentary canal and label - gall bladder, pancreas, liver and small intestine on it.
b. Give two reasons to explain why absorption of digested food occurs mainly in the small intestine.

A small object is placed 150mm away from a diverging lens of focal length 100mm:

1. Copy the figure below and draw rays to show how an image is formed by the lens.

2. Calculate the distance of the image from the lens by using the lens formula.

What changes would you suggest in your home in order to be environment-friendly?