So2cl2 decomposes in a first-order process with a half-life of 4.88 × 103 s. if the original concentration of so2cl2 is 0.011 m, how many seconds will it take for the so2cl2 to reach 0.0032 m?

The amount of substance after n half-lives is calculated through the equation,
                                     A(n) = A(0) x (0.5)^t/h
where A(n) is the amount of n half-lives, A(0) is the original amount, t is the total time and h is the half-life. 
Substituting the known values,
 Basis is 1L,
                           0.0032 = (0.011) x (0.5)^(t/4.88x10^3s)
The value of t from the generated equation is equal to 8693.0 s or also equal to 8.693 x 10^3 s. 

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom.