If $A$ and $B$ are two matrices of the order $3 \times \mathrm{m}$ and $3 \times n$, respectively and $m=n$, then order of matrix $(5 A-2 B)$ is

If $A=\left[\begin{array}{ll}0 & 1 \\ 1 & 0\end{array}\right]$, then $A^2$ is equal to

If matrix $A=\left[a_{i j}\right]_{2 \times 2}$, where $a_{i j}=1$, if $i \neq j=0$ and if $i=j$, then $A^2$ is equal to

The matrix $\left[\begin{array}{ccc}1 & 0 & 0 \\ 0 & 2 & 0 \\ 0 & 0 & 4\end{array}\right]$ is a

The matrix $\left[\begin{array}{ccc}0 & -5 & 8 \\ 5 & 0 & 12 \\ -8 & -12 & 0\end{array}\right]$ is a