Sources of Energy — Science STD 10 — Question

What is meant by positive tropism and negative tropism? Explain with examples.

Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen is possible. State the essential condition for an addition reaction. Stating this condition, write a chemical equation giving the name of the reactant and the product of the reaction.

1. Give the evidence that the birds have evolved from reptiles.
2. Insects, octopus, planaria and vertebrates possess eyes. Can we group these animals together on the basis of eyes that they possess? Justify your answer giving reason.

State the factors on which the strength of an electromagnet depends. How does it depend on these factors?

List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over the past 50 years in our country.

What is the difference between a good conductor and a poor conductor? Give two example of each.

What is a magnetic field? How can the direction of magnetic field lines at a place be determined?

Using electron-dot diagrams which show only the outermost shell electrons, show how a molecule of nitrogen, N, is formed from two nitrogen atoms. What name is given to this type of bonding? (Atomic number of nitrogen is 7)

A lens of focal length 20cm is used to produce a ten times magnified image of a film slide on a screen. How far must the slide be placed from the lens ?

Explain how, a reduction reaction of aluminium can be used for welding cracked machine parts of iron. Write a chemical equation for the reaction involved.