Answer:
He needs to add 4 mL of the 0.5 M solution to 6 mL of water.
Answer: With atomic number 20, calcium atoms have 20 positive protons, and the ion has only 18 electrons, which means the net charge is +2. Calcium ions are essential for muscle contractions, nerve impulses, and bone maintenance.
:
Answer: obey the "law of conservation of mass".
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by radiation from the Earth's surface
