Final answer:
If you are standing on Capricorn on December 21, the length of the daylight hours would be shorter than the nighttime hours.
Step-by-step explanation:
If you are standing on Capricorn on December 21, the length of the daylight hours would be shorter than the nighttime hours. This is because December 21 is the winter solstice in the Northern Hemisphere, and the Tropic of Capricorn is in the Southern Hemisphere. During the winter solstice, the North Pole is in darkness for 24 hours, so the Sun's path is the shortest and the day is at its shortest.