Answer : Lower than the mercury in the vessel, and shaped like the outside of an umbrella.
Explanation : We know that the capillary action, In this the inter-molecular force within the mercury exceed those between the glass and the mercury
Hence, a convex meniscus form and capillary action work in reverse.
So, if a small diameter open glass tube is partially immersed in a vessel containing mercury, the surface of the mercury inside the tube will be lower than the mercury in the vessel, and shaped like the outside of an umbrella.