Volume of mercury in the bulb of a thermometer is ${10}^{-6}{\mathrm{m}}^3$. Area Of cross section of capillary tube is $2\times {10}^{-7}{\mathrm{m}}^2\cdot {\mathrm{\gamma }}_{\mathrm{Hg}}=18\times {10}^{-5}{/}^{\circ }\mathrm{C}$, If temperature is raised by ${100}^{\circ }\mathrm{C}$, length of mercury column raised in to the tube is (neglect expansion of glass) 

 

• A

  9  mm   

• B

  9 cm    

• C

  18  cm   

• D

  18 mm