Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Pangaea began breaking apart 250 million years ago.

Answer: How many millions of years ago did pangaea begin breaking apart?


Question: Half-life property of carbon and other elements can be used to date fossils and rocks, among other things.

Answer: What property of carbon and other elements can be used to date fossils and rocks, among other things?


Question: Ions that contain fewer electrons than protons have a net positive charge and are called cations.

Answer:
Ions that contain fewer electrons than protons have a net positive charge and are called what?