The mass of piece of sterling silver jewelry is 33.24 g. It contains 92.5% silver Ag by mass. Since, sterling silver is an alloy of Ag-Cu thus, percentage of Cu will be:
% Cu=100-92.5=7.5%
Thus, mass of copper will be:

Molar mass of Cu is 63.546 g/mol, thus, number of moles of Cu can be calculated as follows:

Here, m is mass and M is molar mass.
Putting the values,

Now, in 1 mole of Cu there are
thus, in 0.03923 mol, number of Cu atoms will be:

Thus, number of atoms of Cu will be
.
Answer:
V2 = 90.7 mL
Explanation:
pressure and volume are inversely proportional, if the pressure is increased, the volume will decrease. In an isothermal process:
p1V1 = p2V2
V2 = p1V1/p2 = (277 torr×187 mL)/571 torr
V2 = 90.7 mL
Answer:
Explanation:
mass of the reactant = mass of the product
15.31 + 1.50 = 16.81g