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 $ 1\text{ }carbon-\text{ }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 $ 12\text{ }g $ 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 $ 4.50~mol~\times 58.69g\cdot mo{{l}^{-1}} $ , which is approx. $ 270~g $ . 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 $ 58.69~g. $.

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.