Control and Coordination — Science STD 10 — Question

With the help of a labelled diagram, explain why a tank full of water appears less deep than it actually is.

An object placed 20cm in front of a mirror is found to have an image 15cm.

1. In front of it,
2. Behind the mirror.

Find the focal length of the mirror and the kind of mirror in each case.

Explain how, sex is determined in human babies.

Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet gets deflected when a bar magnet or a current carrying loop is brought near it. Describe some salient features of magnetic field lines concept.

Which feature(s) help the plants to make food by the process of photosynthesis?

Metals are said to be shiny. Why do metals generally appear to be dull ? How can their brightness be restored?

Giving reasons, state the ‘signs’ (positive or negative) which can be given to the following:

1. Object distance (u) for a concave mirror or convex mirror.
2. Image distances (v) for a concave mirror.
3. Image distances (v) for a convex mirror.

Identify the acid and the base from which sodium chloride is obtained. Which type of salt is it? When is it called rock salt? How is rock salt formed?

When is a person said to have developed cataract in his eye ? How is the vision of a person having cataract restored?