Human Eye and Colourful World — Science STD 10 — Question

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Give two uses of concave mirrors. Explain why you would choose concave mirrors for these uses.

When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

Explain how harmful chemicals enter our bodies.

An object is 2m from a lens which forms an erect image one-fourth (exactly) the size of the object. Determine the focal length of the lens. What type of lens is this?

A concave mirror produces a real image 1cm tall of an object 2.5mm tall placed 5cm from the mirror. Find the position of the image and the focal length of the mirror.

Draw circuit symbols for:

1. Fixed resistance.
2. Variable resistance.
3. A cell.
4. A battery of three cells.
5. An open switch.
6. A closed switch.

Describe the working of a hydrogen bomb.

When the magnet shown in the diagram below is moving towards the coil, the galvanometer gives a reading to the right.

1. What is the name of the effect being produced by the moving magnet?
2. State what happens to the reading shown on the galvanometer when the magnet is moving away from the coil.
3. The original experiment is repeated. This time the magnet is moved towards the coil at a great speed. State two changes you would notice in the reading on the galvanometer.

Write the formulae of sodium chloride and sodium carbonate. Explain why an aqueous solution of sodium chloride is neutral but an aqueous solution of sodium carbonate is basic (or alkaline). Write chemical equations of the reactions involved.