Question

Identify the wrong statement with reference to UV rays.
(a) UV-A is more harmful to animals than UV-B.
(b) UV radiation falls in the range between 100- 300 nm in wavelength.
(c) UV radiation classified into three categories.
(d) UV radiation kills microorganisms.

Answer 1

Hint: UV radiation is present in sunlight, it is a type of electromagnetic waves lies between visible rays and X-ray with a wavelength of 10- 400 nanometer. It affects the skin and causes various types of skin cancer.

Complete answer:
 Ultraviolet rays are produced from a maximum heated area. Sun is the main source of ultraviolet radiation but a manmade lamp can also produce ultraviolet radiation. A man-made lamp in the case of ultraviolet rays is used for experimental purposes. There are three types of UV rays present UV-A, UV-B, and UV-C. UV-A is the maximum producing UV ray from the sun, its wavelength range between 315- 399 nm. It does not get absorbed by the ozone layer. UV-A use in tanning beds causes skin aging and wrinkling, it is also strongly linked with skin cancer. UV-B has a wavelength range of 280-340 nm. It is mostly absorbed by the ozone layer and only a small amount reaches the earth. UV-B causes cancer, sunburn and it also damages skin DNA. UV-C wavelength range between 100-279 nm. It is totally absorbed by the ozone layer and it does not affect the skin but UV-C rays present in welding torches and mercury lamps are very dangerous. UV radiation also causes eye problems like a cataract in which the eye lens becomes cloudy and if remains untreated the white fluid in the lens is drained out and the person becomes blind.
UV rays also have some beneficial effects like it produce vitamin D which helps in the absorption of calcium and phosphorus from food. It also kills harmful microorganisms.
So, the correct answer is UV-A is more harmful to animals than UV-B.

Note: Ozone is formed by oxygen molecules and with an increase in pollution and deforestation, the layer of ozone becomes thin which causes high absorption of UV radiation leads to global warming, high chances of skin cancer, and impaired immune system.