Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray Group 2 alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust. The ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.[5] Free calcium metal is too reactive to occur in nature. Calcium is produced in supernova nucleosynthesis.
Ah, I'm not sure. I hope someone helps you!
Answer:
i think 1 is either b or d
Explanation:
<span>True. A valid hypothesis must be testable and able to be verified or disputed empirically, because otherwise it is not a scientific hypothesis. A hypothesis that is not readily testable (for example, about a made up or fictional event) are not good hypotheses.</span>
