Consider the given figure,

                                                                 

 

Two volumes of hydrogen react with one volume of oxygen to give two volumes of water vapour.

$\text{ Hydrogen }+\text{ Oxygen }⟶\text{ Water }$

 100 mL              A             100 mL

The volumes of hydrogen and oxygen which combine together bear a simple ratio of . ..B.. . The missing terms A and,B respectively are