Questions

The earth's atmosphere is composed of 4 layers. 

1. Troposphere

2. Stratosphere

3. Ionosphere

4. Mesosphere

The ozone layer is located in the lower region of the Stratosphere which extends at 11 - 50 kms from the Earth's suface.

The shape of two fingers shown up will be in 'V' and it represents in Roman letters, a number 5.

We know that, Elements in the same group of the periodic table have similar characteristics.

Here Magnesium and Strontium shared some similar properties because they both belong to the same group. Sr is the chemical symbol for strontium which is a group two element; it has atomic number of 38. 

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of the real world. Scientific theories are not ever proved in the sense of being proved to be 100% correct.

Examples of some scientific theories are ::

Evolution, gravity, atomic theory, the germ theory of disease, relativity, quantum theory, electromagnetic theory, layered Earth theory, etc...

Demat means Dematerialisation of share, in simple it is an account with which a person can trade in security market without which a person cannot buy or sell any share in security market.