Answer. Ozone is an allotropic form of oxygen consisting of three oxygen atoms. It is formed in atmosphere by the, association of an oxygen atom with an oxygen molecule in the mid of stratosphere.
Ozone is present throughout the atmosphere. But its maximum concentration called ozone layer lies in stratosphere region about 25 to 30 km away from the Earth's surface. This layer surrounds the globe and protects Earth like a shield from harmful ultraviolet radiations of sunlight as shown in figure.
Ultraviolet radiations absorbed by ozone layer