Answer:
Step-by-step explanation:
If the Earth rotated once every 48 hours, the statement that would NOT be true is: "The length of a day would be longer."
The length of a day is determined by the time it takes for the Earth to complete one full rotation on its axis. If the Earth rotated once every 48 hours instead of the current approximate 24 hours, the length of a day would be shorter, not longer. Therefore, the statement that the length of a day would be longer would be false.