Question

Which is not a greenhouse gas
A. Chlorofluorocarbon
B. Methane
C. Carbon dioxide
D. Hydrogen

Answer 1

Hint: Greenhouse gases are responsible for causing the greenhouse effect which is a naturally occurring that is responsible for heating the earth’s surface and atmosphere. Vehicular emissions, fossil fuels burning, as well as some basic processes like respiration, are some of the sources of greenhouse gases.

Complete answer:
Main gases responsible for the greenhouse effect are carbon dioxide(81%), methane(10%), Chlorofluorocarbon or CFCs(3%) and Nitrous oxide(7%). These gases are collectively known as greenhouse gases. They selectively allow the short-wavelength energy to pass through but absorb and reflect back the longer wavelength energy to the earth, thus, heating up the atmosphere. Without the greenhouse effect, the average temperature of the earth’s surface would have been an extremely cold planet rather than the present average of approximately 14°C.
The greenhouse effect is also associated with global warming where an increase in the level of greenhouse gases has led to considerable heating of the earth. Scientists believe that global warming is the reason behind many adverse and odd climatic conditions being witnessed in various parts of the earth. It has also induced the melting of polar ice caps as well as glaciers in Himalayan snowcaps. CFCs have depleted the ozone layer which is present in the stratosphere and protects us from harmful ultraviolet radiation.
To reduce global warming, reducing the usage of fossil fuels is encouraged along with many other steps such as reducing deforestation, improving the efficiency of energy usage, and slowing down the growth of the human population.

So, the correct answer is ‘Hydrogen’.

Note: Ultraviolet rays are highly injurious as they may have deleterious effects on ones’ DNA. It is high energy and can break bonds within these molecules and might induce mutation along with the ageing of skin and cancer. A high dose of UV-B radiation can lead to inflammation of the cornea and ultimately snow-blindness cataract, leading to permanent blindness.