First, let us calculate for the volume of the block of lead using the formula:
V = l * w * h
But we have to convert all units in terms of cm:
l = 2.0 dm = 20 cm
w = 8 cm
h = 3.5 cm
Therefore the volume is:
V = (20 cm) * (8 cm) * (3.5 cm)
V = 560 cm^3
Next we convert the mass in terms of g:
m = 6.356 kg = 6356 g
Density is mass over volume, so:
density = 6356 g / 560 cm^3
density = 11.35 g / cm^3 (ANSWER)