Answer: 70.07 square cm.
Explanation:
First, let's look at the curved part of the cylinder. It's similar to wrapping a present, but instead of wrapping paper, we're measuring the diameter (2 * pi * radius) and height (21 cm). This results in a surface area of 63 pi square cm.
Let's take a look at the circular base next. It's similar to a pizza, and we're calculating the size of the "slice" by multiplying pi (3.14), by the radius of the circle squared (1.5 * 1.5). This offers us a 7.07 square cm area.
Finally, we combine these two components to get the overall surface area, and voilà! 70.07 square cm = 63 pi square cm + 7.07 square cm. The riddle has been solved! The glass cylinder in contact with mercury has a total surface area of 70.07 square cm.