To show the presence of oxygen and nitrogen in air, take a test tube ___ long and fix along its side a ___ long strip graph paper

Phosphorus combines with oxygen to form

Nitrogen helps in burning

To show the presence of carbon dioxide in air, pour ____ ml of _____

in a clean hard glass test tube

Burning of coal releases large amount of ___

Phosphorus Pentoxide Gas combine with water to form

To show the presence of water vapour in air, wipe the glass tumbler from outside so that,

Take a pea sized shape Phosphorus and over it fix a __________

Till the middle of the 19th century, the amount of carbon dioxide was_____.