$A$ vertical glass capillary tube open at both ends contains some water. Which of the following shapes may be taken by the water in the tube?

Why is the refill of a marker pen used to write on a whiteboard made of fibers?

Three liquids have the same surface tension and densities $\varrho_{1}, \varrho_{2}$,and $\varrho_{3}$ $(\varrho_{1} > \varrho_{2} > \varrho_{3})$. In three identical capillaries,the rise of liquid is the same. The corresponding angles of contact $\theta_{1}, \theta_{2}$,and $\theta_{3}$ are related as:

If a capillary tube of radius $1 \,mm$ is immersed in water, the mass of water rising in the capillary tube is $m$. If the radius of the capillary tube is doubled, then the mass of water that rises in the same capillary tube will be

On putting a capillary tube in a pot filled with water,the level of water rises up to a height of $4 \,cm$ in the tube. If a tube of half the diameter is used instead,the water will rise to a height of nearly ............. $cm$.

It is not possible to write directly on blotting paper or newspaper with an ink pen.