The opposite of the right ideal in the ring of 2x2 matrices?

Question

Since every ring has an opposite, I would like to know:

1. Which is the opposite of the rings of $n \times n$ matrices? More specifically, of the $2 \times 2$ matrices.

2. Is there an opposite for the right ideal of rings of $2 \times 2$ matrices which is made up of a matrix with zeroes in the bottom row? If so, which one?

Thanks in advance.