When a liquid is heated in copper vessel its coefficient of apparent expansion is $6 \times 10^{-6} /{ }^{\circ} \mathrm{C}$. When the same liquid is heated in a steel vessel its coefficient of apparent expansion is $24 \times 10^{-6} /{ }^{\circ} \mathrm{C}$. If coefficient of linear expansion for copper is $18 \times 10^{-6} /{ }^{\circ} \mathrm{C}$, the coefficient of linear expansion for steel is

• A

  $20 \times 10^{-6} /{ }^{\circ} \mathrm{C}$
• B

  $24 \times 10^{-6} /{ }^{\circ} \mathrm{C}$
• C

  $36 \times 10^{-6} /{ }^{\circ} \mathrm{C}$
• Correct answer
  D

  $12 \times 10^{-6} /{ }^{\circ} \mathrm{C}$

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