P-1 Gravitation — Science STD 10 — Question

Observe the given figure of reactivity series of metals and answer the following questions:
Reactivity series of metals
Name two metals which react with water.
Name two moderately reactive metals.
Name the most highly reactive metal and the most less reactive metal.

A man can read the number of a distant bus clearly but he finds difficulty in reading a book.A man can read the number of a distant bus clearly but he finds difficulty in reading a book.

1. From which defect of the eye is he suffering?
2. What type of spectacle lens should he use to correct the defect?

A bulb of 60 W is connected across a source of 240 V. Find the resistance of the bulb.

By observing given picture, write any two effects of this disaster:

Give two examples of thermal decomposition.

If a convex lens of focal length 10 cm and a concave lens of focal length 50 cm are kept in contact with each other, (i) what will be the focal length of the combination? (ii) what wiil be the power of the combination? (iii) what will be the behaviour of the combination (behaviour as a convex lens/concave lens)?

A boy with a mouth 5cm wide stands 2m away from a plane mirror. Where is his image and how wide is the image of his mouth?

What is the periodic trend observed in the variation of atomic radii down a group?

Why does the sun appear red at sunrise?