Based on the above Cartesian plane:

The co-ordinates of the point $\mathrm{E}$ are $($ $, -2)$.

Based on the above Cartesian plane, if the co-ordinates of point $\mathrm{F}$ is $\left(a,b\right)$ then the value of $a=$ _____.

Based on the above Cartesian plane, the co-ordinates of point $\mathrm{G}$ are $(2$, _____$)$.