Answer:
[OH-] = 6.17 *10^-10
Explanation:
Step 1: Data given
pOH = 9.21
Step 2: Calculate [OH-]
pOH = -log [OH-] = 9.21
[OH-] = 10^-9.21
[OH-] = 6.17 *10^-10
Step 3: Check if it's correct
pOH + pH = 14
[H+]*[OH-] = 10^-14
pH = 14 - 9.21 = 4.79
[H+] = 10^-4.79
[H+] = 1.62 *10^-5
6.17 * 10^-10 * 1.62 * 10^-5 = 1* 10^-14
If we have 321 grams of a liquid, and the density is 0.84 g/mL, then we can easily find the volume of the liquid. We just need to take this 0.84 and multiply that by the number of grams. If we do 321 * 0.84, we get 269.64 mL. This is the volume that this liquid has.Remember this equation for future problems: V = D*M. V meaning volume, D meaning density, and M meaning mass. I hope this helps.
<u>Answer:</u> The number of gold atoms per cubic centimeters in the given alloy is 
<u>Explanation:</u>
To calculate the number of gold atoms per cubic centimeters for te given silver-gold alloy, we use the equation:

where,
= number of gold atoms per cubic centimeters
= Avogadro's number = 
= Mass percent of gold in the alloy = 42 %
= Density of pure gold = 
= Density of pure silver = 
= molar mass of gold = 196.97 g/mol
Putting values in above equation, we get:

Hence, the number of gold atoms per cubic centimeters in the given alloy is 