<span> (0.20948 x 31.998) / (
(0.78084 x 28.013) +
(0.20948 x 31.998) +
(0.00934 x 39.948) +
(0.000375 x 44.0099) +
(0.00001818 x 20.183) +
(0.00000524 x 4.003) +
(0.000002 x 16.043) +
(0.00000114 x 83.80) +
(0.0000005 x 2.0159) +
(0.0000005 x 44.0128) ) = 0.23140 = 23.140% O by mass </span>
Because the molecules are more spread apart.
(gas spread)
According to Arrhenius theory of acid and bases, an acid is a proton donor, while base donates hydroxyl ions. Further, acid and base reacts to form salt and water.
Consider following example.
HCl + H2O → Cl- + H3O+
here, HCl has donated a proton, hence it is an acid.
Now consider following reactionHCl + NaOH ↔ NaCl + H2O
in this reaction, HCl donates proton, hence it is acid. On other hand, NaOH donates hydroxyl ion (i.e. OH-), hence it is a base.