Bromine has two naturally occurring isotopes (and ) and has an atomic mass of 79.904 . The mass of is 80.9163 , and its natural abundance is 49.31%.Calculate the mass of .Br-79 Express your answer using four significant figures. also Calculate the natural abundanc.

Bromine has two naturally occurring isotopes (and ) and has an atomic mass of 79.904 . The mass of first isotopes  is 80.9163 , and its natural abundance is 49.31%.Calculate the mass of .Br-79 Express your answer using four significant figures. also Calculate the natural abundanc.

the atomic mass of first isotopes       (M1)       =80.9163
the atomic mass of second isotopes (M2)        = ?

average atomic mass of  Bromine     (M )        = 79.904

C1 is the abundance % of first isotopes
abundance  % of second isotopes C2 = 100 - C1
                                                         = 100 - 49.31
                                                         = 50.69%  answer

average atomic mass  = (M1*C1+M2*C2)/100

plug the value in this formula we get

Bromine has two naturally occurring isotopes (and ) and has an atomic mass of 79.904 . The mass of is 80.9163 , and its natural abundance is 49.31%.Calculate the mass of .Br-79 Express your answer using four significant figures. also Calculate the natural abundanc.

balance the oxidation reduction PbO2 yields Pb2+ + O2

Answer :-

oxidation number of oxygen in compound state is -2 

so the oxidation number of Pb in PbO2 

Pb + 2(-2)  = 0 

             Pb = 4 

and Pb +2 has oxidation number +2 

              change in oxidation number is 2-4 = - 2  (reduction )

oxidation number of oxygen in O2 is 0 

so change in oxidation of oxygen is  0- (2)  = 2 (oxidation )

and there are oxygen atom there

                so change in oxidation number is = 2* 2 

                                                                      = 4 

 there ratio of oxidation and reduction is  4  :  2   = 2  :   1  

cross multiply by these relation we get