A solid cube of mass $m$ at a temperature $\theta_0$ is heated at a constant rate. It becomes liquid at temperature $\theta_1$ and vapour at temperature $\theta_2$. Let $s_1$ and $s_2$ be specific heats in its solid and liquid states respectively. If $L_f$ and $L_v$ are latent heats of fusion and vaporisation respectively, then the minimum heat energy supplied to the cube until it vaporises is

• A

  $m s_1\left(\theta_1-\theta_0\right)+m s_2\left(\theta_2-\theta_1\right)$
• B

  $m L_f+m s_2\left(\theta_2-\theta_1\right)+m L_v$
• Correct answer
  C

  $m s_1\left(\theta_1-\theta_0\right)+m L_f+m s_2\left(\theta_2-\theta_1\right)+m L_y$
• D

  $m s_1\left(\theta_1-\theta_0\right)+m L_f+m s_2\left(\theta_2-\theta_0\right)+m L_v$

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