To determine the mass of soil in an acre 6 inches deep with a bulk density of 1.2 g/cm3, the volume must first be calculated. An acre has a volume of 21,780 ft3 when considering half an acre. The conversion from cubic feet to cubic centimeters is essential, as 1 cubic foot equals 28,316.8466 cm3. The mass can then be calculated using the formula that incorporates the bulk density and the converted volume. Accurate unit conversions are crucial for solving this density mass problem effectively.