\[\boxed{\mathbf{1}\mathbf{.212}}\]
\[\textbf{а)}\ 46 + 789 = 467 + 89\]
\[Неверно.\]
\[\textbf{б)}\ 246\ :6 - 24 < 357\ :7\]
\[41 - 24 = 17\]
\[357\ :7 = 51\]
\[17 < 51\]
\[Верно.\]
\[\textbf{в)}\ 34 \cdot 79 > 63 \cdot 42\]
\[Верно.\]
\[\textbf{г)}\ 12 \cdot 3 + 45 \cdot 6 \cdot 1 > 23 + 4 \cdot 56\]
\[36 + 270 > 23 + 224\]
\[Верно.\]