A block of wood is floating on water at 0 ° C with volume V _ 0...

As temnerature of water is increased from $0 ° C$ to $10 ° C$, density of water initially increases upto a maximum at $4 ° C$ and then it reduces.
So, buoyant force on block of wood also increases till temperature reaches $4 ° C$ and then decreases from $4 ° C$ to $10 ° C$.
Hence, volume of block above water also increases upto $4 ° C$ and then decreases from $4 ° C$ to $10 ° C$

$∴$ Variation of ${V}_{0}$ versus $t$ as shown below.