A $20\text{ cm}$ long capillary tube is dipped in water. The water rises up to $8\text{ cm}$. If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be:

The height of liquid rise in a capillary is $h=\frac{2T\cos \theta }{r\rho g}$.In a freely falling elevator, the effective acceleration due to gravity $g_{eff}=g-g=0$.As $g\to 0$, $h\to \infty$. This means the water will rise to the maximum available length of the tube.Since the tube is $20\text{ cm}$ long, the water column will be $20\text{ cm}$.