Sources of Energy — Science STD 10 — Question

List two main causes of a person developing near sightedness. Show with the help of a ray diagram how this defect can be corrected.

What is yeast? Describe the process of reproduction in yeast with the help of labelled diagrams.

What is saponification? Write the chemical equation of the reaction involved in this process. Name all the substances which take part in this process and also those which are formed.

Name three common methods which are used for the artificial propagation of plants.

A person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?

Do non-metals possess lustre? Give two exceptions of this property of non-metal.

How do the insects help in cross-pollination?

Write the sex of the baby that inherits Y-chromosome from the father.

Define the reproductive health.

How will you distinguish between a plane mirror, a concave mirror and a convex mirror without touching them?