Electricity — Science STD 10 — Question

An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving reason: Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.

Describe and explain, how a normal eye can see objects lying at various distances clearly.

A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.

How do human activities affect the environment?

What is a good source of energy?

How does the size of atoms (atomic size) generally vary in going from left to right in a period of the periodic table? Why does it vary this way?

Name the 3 Rs' that will help us to conserve natural resources for long-term use.

A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?

Explain how tidal energy can be used to generate electricity.

What is the nuclear fuel in the sun? Describe the process by which energy is released in the sun. Write the equation of the nuclear reaction involved.