A black coloured solid which on reaction with dilute sulphuric acid forms a blue coloured solution is 

Name the method used for the preparation of sodium nitrate from the list given below:

Select the words which are required to correctly complete the blanks.

[ammonia, ammonium carbonate, carbon dioxide, hydrogen, hydronium, hydroxide, precipitate, salt, water]

If a piece of magnesium was put into a solution M (acid) _____ gas would be evolved.

Give a suitable chemical term for 

The process in which a substance absorbs moisture from the atmospheric air to become moist and ultimately dissolves in the absorbed water.