Using the equation 2h2+o2=2h2o, when 47g of water are produced, how many grams of hydrogen must react?

See , from the equation we can see that for forming two mole of H2O 2Mole of H2 has to react.

Mass of 2 Mole H2O is 18*2gm or 36gm.

So for forming 36 gm H2O 2×2 I.e. 4 gm H2 has to take part in reaction.

Therefore, to form 1 gm H2O 4÷36 gm of H2 has to take part.

So, for forming 47gm H2O (4÷36)×47 gm H2 has to take part

I.e. 5.22 gm of H2 has to take part

So, ans is 5.22 gm of hydrogen.

Hope it helps!!!

it's c. elements are placed in rows based on how may valencies electrons have.

particle   p is an electron and particle q is a neutron