\[\boxed{\mathbf{1.}\mathbf{120}}\]
\[\textbf{а)}\ 1\ кг = 1000\ г\]
\[8 \cdot 100\ :1000 = 0,8\%.\]
\[\textbf{б)}\ 1\ ч = 60\ мин\]
\[15 \cdot 100\ :60 = 150\ :6 = 25\%.\]
\[\textbf{в)}\ 1\ км = 1000\ м\]
\[15 \cdot 100\ :1000 = 1,5\%.\]
\[\textbf{г)}\ 1\ м^{3} = 1000\ л\]
\[300 \cdot 100\ :1000 = 30\%.\]