$($a$)$ Check the stability $($overturning$,$ sliding, bearing capacity$)$ of the gravity wall$-$backfill system shown in Figure $2,$ with the data given in Table $2,$ and state if the selected dimensions are safe or not $($Use Coulomb's theory of earth pressures$).$

$\frac{V}{m^3}$

Figure $2.$ Gravity retaining wall.