Question

A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Answer 1

Mass of silver = m g 

Mass of gold = m /100g 

Number of atoms of silver =  Mass/ Atomic mass X N_A  

                                                   =  m /108N_A  

Number of atoms of gold = m/ 100 X197  

Ratio of number of atoms of gold to silver = Au : Ag 

= m/ 100 X 197 X N_A : m/ 108 N_A

= 108 : 100×197 

= 108 : 19700 

= 1 : 182.41