Q. 6

# When a capillary tube is dipped into a liquid, the liquid neither rises nor falls in the capillary.

A. The surface tension of the liquid must be zero.

B. The contact angle must be 90^{o}.

C. The surface tension may be zero

D. The contact angle may be 90^{o}.

Answer :

If the level of liquid does not rise, it may be assumed that the surface tension is zero or the angle of contact is 90°, or both. Although it cannot be said with certainty whether the surface tension or the angle of contact is 90°.

Hence, both the option C and D is correct.

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