Two or more compounds that have same molecular formula but differ in the arrangement of atoms in molecule and thus posses different properties are known as isomers.
The molecular formula of pentane is 
substituting one hydrogen from pentane with bromine results in the formation of monobromo derivatives of pentane having molecular formula, 
.
The structure of monobromo derivatives of pentane that is 1-bromopentane, 2-bromopentane, and 3-bromopentane and having molecular formula, is shown in the image.
The other two arrangements of monobromo derivatives of pentane that is 2-bromo-2-methylbutane and 2-bromo-3-methylbutane is shown in the image.
There are different structures of monobromo derivatives of pentane having molecular formula, which contain a 4-carbon chain are 1- bromo-2-methylbutane and 1-bromo-3-methylbutane shown in the image.
Answer:
The size of an atom can be estimated by measuring the distance between adjacent atoms in a covalent compound. The covalent radius of a chlorine atom, for example, is half the distance between the nuclei of the atoms in a Cl2 molecule.
A Change of Course. Light travels faster through air than it does through a denser substance, such as water or glass.
So, when light rays travel through air and meet the surface of the denser substance, they are suddenly slowed down.
When this happens, the light rays bend.
