What is added to purify the water?
copper sulphate
potassium nitrate
ammonia
alum
What is as important as air for our survival?
heat
light
water
cloth
The purest form of natural water is:
rain water
pond water
sea water
well water
What is taken from the inhaled air by the blood in our lungs?
oxygen
hydrogen
nitrogen
carbondioxide
The amount of water vapour present in the air is called:
humidity
viscosity
fluidity
density
Which of the following is used to inflate footballs and tubes of vehicles?
sand
soil
mud
air
What crystals are added in well to purify water?
potassium permanganate
sodium hydroxide
potassium dichromate
Which is the fifth layer of the atmosphere?
exosphere
thermosphere
troposphere
stratosphere
What do we call the fresh air that we breath?
inhaled
exhaled
expired
burned
The most important gas for the survival of living beings is:
argon
