Answer
$58.8\space N$
Work Step by Step
Here we use the Archimedes principle to find the buoyant force that acts on the block.
$F_{B}=V\rho_{w}g$ ; Let's plug known values into this equation.
$F_{B}=(0.1\times0.2\times0.3)\space m^{2}(1000\space kg/m^{3})(9.8\space m/s^{2})=58.8\space N$
