Answer: Height of the block of southern pine is 7 cm.
Explanation:
Since we have given that
Mass = 54.6 g
Density = 0.65 g/cm³
First we calculate the "Volume ":

Length of rectangular prism = 4 cm
Width of rectangular prism = 3 cm
Height of rectangular prism be 'h'.
So, Volume of rectangular prism = Length×Width×Height

Hence, height of the block of southern pine is 7 cm.