Excess electrons are placed on a small lead sphere with a mass of 7.70 g so that its net charge is −3.35 × 10^−9 C. A) Find the number of excess electrons on the sphere. B) How many excess electrons are there per lead atom? The atomic number of lead is 82, and its atomic mass is 207 g/mol?

a

b

Explanation:

From the question we are told  that

   The  mass of the lead sphere is  

   The net charge is

   The  atomic number is  

     The  molar mass is  

Generally the excess number of  electron on the sphere is mathematically represented as

Here e is the charge on the electron is  

     So

Generally the number of atom present is mathematically represented as  

Here is the Avogadro's number with value  

Generally the electrons are there per lead atom is mathematically represented as

=>  

=>    

total distance/total time

(85 + 82)/(5+3)

167/8

20 just over

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.