Question

A quarter is composed of $4.50$ moles of nickel. How many atoms of nickel do this equal?

Answer 1

Hint :We know that Avogadro’s number is the number of molecules present in one mole which is equal to entities. It is denoted by the symbol $N_A$ . This value is directly used to find the number of atoms in certain different types of molecules which have different representational units.

Complete Step By Step Answer:
Everything present in this universe is made up of atoms. The mass of an atom cannot be measured truly due to its very small size. So a relative term is used for it called relative atomic mass. It is based on the mass of $1carbon-12$ atom.
Mole is the amount of substance that contains the atoms, molecules or other particles in an entity equal to the atoms present in $12g$ of $C-12$ isotope. It defines the basis of physical chemistry and so its number is called Avogadro's number which is equal to $6.022\times {10}^{23}$ entities. It is denoted by the symbol $N_A.$
 $4.50$ moles of $Ni$ has a mass of $4.50mol\times 58.69g\cdot mo{l}^{-1}$ , which is approx. $270g$ . If we are talking about American currency, I am pretty sure that nickels (and dimes and quarters) are not so massive.
It is a fact that if there are mol of stuff, there are $6.022\times {10}^{23}$ items of that stuff. So you do the arithmetic.
Therefore, One mole of nickel has a mass of $58.69g.$.

Note :
Mole is not only related to mass but also to volume as any matter that has a certain mass will occupy a certain volume. One mole is the amount of molecules present in $22.4$ litres of a gas calculated at standard temperature and pressure.