Final answer:
The Apollo 12 mission conducted two extravehicular activities on the Moon, contrary to the statement provided.
Step-by-step explanation:
The statement that is not true about the Apollo 12 mission is: As had been the case with the Apollo 11 mission, the two Apollo 12 astronauts who landed on the Moon completed just one period of extravehicular activity outside the lunar module. In reality, the Apollo 12 astronauts conducted two extravehicular activities (EVAs) on the Moon. During the EVAs, they collected samples, performed experiments, and repaired the Surveyor 3 spacecraft.
Learn more about Apollo 12 mission