Answer:
44.625862500000004 grams are in 0.376 mol Kbr! Plz mark as brainliest, hope this helped you!
See the correct answer is b.)PbS
Nitrogen and Oxygen react to form Nitrogen Oxides. These gasses irritate the lungs and cause acid rain.
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
.
It is an alkaline earth metal.