The solubility of an ionic compound can be expressed as the number of moles of the compound that will dissolve per liter of solution (molarity). The saturated solution has approximately(a) sodium ions dissolved in it (give an estimate of the average value.) The solution (not the solid) contains approximately(b) moles of sodium ions.

Number of moles  of sodium dissolved =  6.0 *10^23

Explanation:

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Solution

a) Total 181 ions of Na are dissolved

b)

The number of moles of sodium dissolved = 181/6.023 *10^23

Number of moles  of sodium dissolved = 5.987 * 10^23

Number of moles  of sodium dissolved =  6.0 *10^23

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

the answer to this question is 3.