If a $4 \mathrm{~kg}$ of ice is inside a closed cubical thermocol box of side length $20 \mathrm{~cm}$ and wall thickness $4 \mathrm{~cm}$ then the mass of the ice remaining after 10 hours is nearly (The out side temperature $=50^{\circ} \mathrm{C}$ co-efficient of thermal conductivity of thermocol $=0.01 \mathrm{Js}^{-1} \mathrm{~m}^{-1{ }^{\circ}} \mathrm{C}^{-1}$ Latent heat of fusion of ice $=335 \times 10^3 \mathrm{~J} \mathrm{~kg}^{-1}$)

• Correct answer
  A

  $3.678 \mathrm{~kg}$
• B

  $6.378 \mathrm{~kg}$
• C

  $2.87 \mathrm{~kg}$
• D

  $1.87 \mathrm{~kg}$

Hence, the correct answer is option: 'A'.