The molar mass of NaCl is 23 + 35.5 = 58.5 g/mol, so the mass of the sample ia 0.78 × 58.5 = 45.63 g.
Stoich questions...
1) convert the grams of Au to moles
(33.5g)/(196.7g/mol)=___x___
2)find how many atoms are in that many moles by multiplying it by avogadro's number.
x(moles of Au)*(6.02*10^23)=?
3)now that you have found the number of atoms of gold, convert it to grams of aluminum by multiplying it by Avogadro's number and multiplying it by the atomic mass of aluminum.
( ? )(6.02*10^23)(26.98g/mol)= (mass of Al)
Answer:

Explanation:
Hello,
In this case, the Boyle's is mathematically defined via:

Which stands for an inversely proportional relationship between volume and pressure, it means the higher the volume the lower the pressure and vice versa. In such a way, since the volume is decreased to one quarter, we can write:

We can compute the new pressure:

Which means the pressure is increased by a factor of four.
Regards.