This drawing represents a comet bringing atmospheric molecules and possibly primitive life forms to the Earth's surface.
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Base

Like an acid, a base is a substance capable of dissolving things.

There are many bases. Here are a few: Ammonia (used as a cleaner), Calcium hydroxide (used in mortar for construction), Magnesium hydroxide (otherwise known as milk of magnesia; used as a laxative or antacid), Sodium hydroxide (used as an oven cleaner).


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