Question

If sufficient acid is used to react completely

Answer 1

Solution,

Mass of Mg - 21gm

molar mass of Mg - 24gm

moles = Given mass/ Molar mass

moles = 21/24 = 0.875

1 mole of Mg produce 1 mole of H2 gas

so 0.875 mole of Mg will produce 0.875 moles of H2 gas

One mole of H2 gas = 22.4 litre

0.875 mole of H2 gas = 0.875×22.4

0.875 mole of H2 gas = 19.60 litre

So the nearest ANSWER is Option four 19.37 litre.