What is the concentration of K+ in 0.15 M of K2S?

What is the concentration of K+ in 0.15 M of K2S?
If CaCl2 is dissolved in water, what can be said about the concentration of the Ca2+ ion?
It has the same concentration as the Cl− ion.
Its concentration is half that of the Cl− ion.
Its concentration is twice that of the Cl− ion.
Its concentration is one-third that of the Cl− ion.
A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4 will be needed to produce 575 mL of a solution that has a concentration of Na+ ions of 0.600 M ?
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Answer:

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