The correct answer would be D. Ca^2+ has 18 electrons. This is because 2+ means that 2 electrons have been removed, and Ca starts out with 20 electrons. As 20 - 2 = 18 electrons, D is the correct answer.
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Answer:
Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland. Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up
On September 27, 2015, a rare total lunar eclipse of a supermoon occurred. A supermoon occurs when the entire lighted half of the Moon faces Earth (full Moon phase) and the Moon is at its closest point to Earth in its orbit.
