Heredity and Evolution — Science STD 10 — Question

Explain why, a stick half immersed in water appears to be bent at the surface. Draw a labelled diagram to illustrate your answer.

1. Draw a ray diagram to show the refraction of light through a glass slab and mark angle of refraction and the lateral shift suffered by the ray of light while passing through the slab.
2. If the refractive index of glass for light going from air to glass is 3/2, find the refractive index of air for light going from glass to air.

Food does not pass through the digestive system by 'gravity'. This is clear from the fact that we can digest the food even if we are lying down. Explain the logic behind the passage of food through our digestive system.

How do metals reacts with dilute acids? Explain with the help of an example.

During extraction of metals, electolytic refining is used to obtain pure metals.

1. Which material will be used as anode and cathode for refining of silver metal by this process?
2. Suggest a suitable electrolyte also.
3. In this electrolytic cell, where do we get pure silver after passing electric current?

A convex lens of focal length 25cm and a concave lens of focal length 10cm are placed in close contact with one another.

1. What is the power of this combination?
2. What is the focal length of this combination?
3. Is this combination converging or diverging?

Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever may be angle of incidence. Show the same with the help of diagram.

What is electroplating?

What is a soap? Name one soap.

State the various steps involved in the process of photosynthesis.