<em>The student should record 20 mL as the correct volume.</em>
The curved surface of a liquid that is usually observed in a buret is referred to as the meniscus. This meniscus is created as a result of the surface tension of the liquid against the walls of the buret. <u>Hence, in order to avoid errors due to parallax, the bottom of the meniscus should be read and not the top.</u>
Therefore, the correct volume that the student should record is 20 mL.
