a.
\[\begin{aligned} \mathrm{pH} &= \mathrm{pH} = 14,00 - \mathrm{pOH} = 14,00 - 2,25 = 11,75 \\ [\mathrm{H_3O^+}] &= 10^{-\mathrm{pH}}\mathrm{mol/dm^3} = 10^{-11,75}\mathrm{mol/dm^3} = \\ &= 1,77828 \cdot 10^{-12}\mathrm{mol/dm^3} ≈ 1,8 \cdot 10^{-12}\mathrm{mol/dm^3}\end{aligned}\]
b.
\[\begin{aligned} \mathrm{pH} &= \mathrm{pH} = 14,00 - \mathrm{pOH} = 14,00 - 10,63 = 3,37 \\ [\mathrm{H_3O^+}] &= 10^{-\mathrm{pH}}\mathrm{mol/dm^3} = 10^{-3,37}\mathrm{mol/dm^3} = \\ &= 0,00042658\mathrm{mol/dm^3} ≈ 0,00043\mathrm{mol/dm^3}\end{aligned}\]
c.
\[\begin{aligned} \mathrm{pH} &= \mathrm{pH} = 14,00 - \mathrm{pOH} = 14,00 - 6,27 = 7,73 \\ [\mathrm{H_3O^+}] &= 10^{-\mathrm{pH}}\mathrm{mol/dm^3} = 10^{-7,73}\mathrm{mol/dm^3} = \\ &= 1,86209 \cdot 10^{-8}\mathrm{mol/dm^3} ≈ 1,9 \cdot 10^{-8}\mathrm{mol/dm^3}\end{aligned}\]
d.
\[\begin{aligned} \mathrm{pH} &= \mathrm{pH} = 14,00 - \mathrm{pOH} = 14,00 - (-1,05) = 15,05 \\ [\mathrm{H_3O^+}] &= 10^{-\mathrm{pH}}\mathrm{mol/dm^3} = 10^{-15,05}\mathrm{mol/dm^3} = \\ &= 8,91251 \cdot 10^{-16}\mathrm{mol/dm^3} ≈ 8,9 \cdot 10^{-16}\mathrm{mol/dm^3}\end{aligned}\]
