2. A considerable part of the harmful ultraviolet radiation of the sum does not reach the earth surface, because of the fact that, there is a layer of __________ high above earth's atmosphere, which absorbs it.
5. 'Safe limit' called Threshold Limit Value (TLV) of carbon monoxide in atmospheric air is < 50 ppm. The main source of carbon monoxide pollutant in air is the
A. The concentric layer in atmosphere which contains about 70% of the total mass of atmosphere and characterised by a steady decrease in temperature is called stratosphere.
B. Stratosphere is rich in ozone and is located just above the troposphere.
C. Troposphere is a turbulent dusty zone containing much of water vapor and clouds.
D. The earth's atmosphere is an envelope of gases extending upto a height of about 200 kms.
Correct Answer: The concentric layer in atmosphere which contains about 70% of the total mass of atmosphere and characterised by a steady decrease in temperature is called stratosphere.
10. Radioactive solid nuclear wastes are disposed off by