Question

Dobson unit is used in the measurement of _________ level.
A. Chlorofluorocarbons
B. Nitrous oxides
C. Ozone
D. UV-B radiations

Answer 1

Hint: Solar rays contain several radiations that are harmful to our body. Most of them are reflected and do not reach the earth surface. Ultraviolet rays are one among them. The Ozone layer present in our atmosphere has a major role in protecting us from these harmful radiations.

Complete Answer:
- Ozone layer is seen in the upper part of the atmosphere called the stratosphere. The layer of atmosphere enveloped by ozone is commonly called the ozone layer or ozone umbrella. It plays a vital role in protecting organisms from harmful UV radiations.
- Know that ultraviolet radiations that are harmful to us are completely absorbed by the ozone layer. But the ozone layer is getting destroyed these days and that may result in serious health hazards. Ozone gas is formed by the action of ultraviolet rays on molecular oxygen present in the atmosphere.
- Meanwhile, its destruction also occurs simultaneously. The balance between the production and destruction of ozone is important for its efficiency to act as an insulator against these harmful radiations. The thickness of the ozone in the stratosphere is measured in Dobson units.
- Chlorofluorocarbons are chemical substances that are emitted to the atmosphere by us that depletes the ozone layer. They are released from types of equipment used by us like air conditioners and refrigerators. These gases contain chlorine and by entering into a chain reaction, they are capable of destroying the ozone layer.

Hence the correct option is C.

Note: Keep in mind that other than good ozone that protects us from harmful radiations, bad ozone is also present. It is found in the troposphere and is harmful to plants and animals. Ultraviolet rays emitted from the sun are capable of breaking chemical bonds of proteins and DNA.