A glass tube of smaller diameter is used while performing an experiment for the capillary rise of water because

it is easier to see through the glass tube
glass tube is cheaper than a metallic tube
it is not possible to conduct this experiment with any other tube
all of the above
✅ The correct answer is option A.

The tangential velocity of the water element having a free vortex is

directly proportional to its distance from the centre
inversely proportional to its distance from the centre
directly proportional to its (distance)2 from the centre
inversely proportional
✅ The correct answer is option B.