Answer:
C. hydration number
Explanation:
When we dissolve an ionic compound (a charged species) the charges can <u>interact with the water molecule</u>. In the case of <u>cations</u> (positive charges) the negative <u>dipole</u> of water (generated in the oxygen) will interact with the positive charge at the same time the <u>anions</u> (negative charges) the positive <u>dipole</u> of water (generated in the hydrogen).
The amount of water molecules that can interact with a single ion (cation or anion) is called <u>hydration number</u>. In the example, we have a hydration number of "4" for the sodium cation.
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Answer:


Explanation:
Hello,
At first, it turns out convenient to compute the total moles of sodium that will be dissolved into the solution by considering the added amounts of sodium bromide and sodium sulfate:

Once we've got the moles we compute the final volume via:

Thus, the molarity of the sodium atoms turn out into:

Now, we perform the same procedure but now for the bromide ions:

Finally, its molarity results:

Best regards.
The moles of silicon is 4.651 moles
<u><em>calculation</em></u>
The moles of silicon is calculated using Avogadro's constant
that is according to Avogadro's law
1 mole = 6.02 x 10^23 atoms
? moles = 2.80 x 10 ^24 atoms of silicon
by cross multiplication
= [ ( 1 mole x 2.80 x 10^24 atoms) / ( 6.02 x 10 ^23 atoms)]
= 4.651 moles