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:
Element
magnesium, hydrogen, chlorine, sulfur
Compound
water, iron oxide
Mixture
air, salty water , dias cola.
Explanation:
Element is made up of only one type of atom and are relresented by symbols.
Compound are formed by chemical mixing of atoms of elements and have a chemical formula
Mixture are formed by simple mixing up of substances and mixture don't have chemical formula.
The equation N2+H2= NH3 is balanced. This is because N2 + 3H^2 ➡️ 2NH^3
Answer:
Any substance that cannot be decomposed into simpler substances by ordinary chemical processes.
Another definition:
An element is the simplest pure substance which can neither be split nor built up from other simpler substances by chemical reaction
