i): 6-4.5/3min=0.5 g/min
ii): Reaction started with 6g of Mg
In that 1.5g of Mg was used
1 mole of Mg is 12g so 1.5g means 0.125 mole
For each Mg atom 2 H atom is used
so for 0.125 mole of Mg 0.25 mole of H is used
That is 0.25 g of H
Therefore rate of production of H2 is 0.083 g/min
