Answer: Option C
Volume of cube = Volume of sheet = (27 × 8 × 1) cm3 = 216 cm3
Edge of cube :
$$\root 3 \of {216} \,cm = 6\,cm$$
Surface area of sheet :
$$\eqalign{
& = 2\left( lb + bh + lh \right) \cr
& = 2\left( {27 \times 8 + 8 \times 1 + 27 \times 1} \right){\text{ c}}{{\text{m}}^2} \cr
& = \left( {216 + 8 + 27} \right){\text{ c}}{{\text{m}}^2} \cr
& = 502{\text{ c}}{{\text{m}}^2} \cr} $$
Surface area of cube :
$$\eqalign{
& = 6{a^2} \cr
& = \left( {6 \times {6^2}} \right){\text{ c}}{{\text{m}}^2} \cr
& = 216{\text{ c}}{{\text{m}}^2} \cr} $$
∴ Required difference :
$$\eqalign{
& = \left( {502 - 216} \right){\text{ c}}{{\text{m}}^2} \cr
& = 286{\text{ c}}{{\text{m}}^2} \cr} $$