Avagadros number is where 1 mol of any substance is made of 6.022 x 10²³ units. These units could be atoms making up an element of molecules making up a compound. 1 mol of Br₂ is made of 6.022 x 10²³ molecules of Br₂ the flask contains 0.100 mol Therefore if 1 mol has 6.022 x 10²³ molecules of Br₂ then 0.1 mol has - 6.022 x 10²³ molecules/mol x 0.1 mol therefore number of molecules - 6.022 x 10²² Br₂ molecules ₂
