What element has the symbol 'Ca'?

The story behind the answer

Ca is the symbol for calcium, an alkaline earth metal (atomic number 20). The other options have different symbols: cobalt is Co, cadmium is Cd, and californium is Cf. A quick mnemonic: Ca = CAlcium, Co = CObalt, Cd = CaDmium, Cf = CaliFornium.

Calcium’s name comes from Latin calx (lime), reflecting its presence in limestone and chalk (calcium carbonate). It’s essential for bones and teeth and helps muscles and nerves function. Because it’s quite reactive, pure calcium isn’t found free in nature; it’s locked in minerals like limestone and gypsum. Memory tip: think “Ca” as in “cAlcium” and “cAlcium in milk and chalk,” both classic sources linked to calcium compounds.