c
(c)
Mass $\times g=$ Volume of part of cube $\times \rho \times g$
$\Rightarrow 200 \times g=L^2\left(2 \times \rho_w \times g\right)$
$\Rightarrow 100=L^2 \quad\left\{\because \rho_w=1\right\}$
$\Rightarrow 10 \,cm =L$
From the two figures we can see that the $200 \,gm$ block is provided with required buoyant force but a part of cube which is afloat in $2^{\text {nd }}$ figure.
