Can anyone solve this please. I need this fastly

Average atomic mass = 63.3896

Explanation:

Step 1: Find how much Cu-65 we have

1 - Amount of Cu-63 = Amount of Cu-65

1 - 0.6915 = Amount of Cu-65

Amount of Cu-65 = 0.305

Step 2: Find the average atomic mass of Cu

(0.6915 x 63) + (0.305 x 65) = Average atomic mass

(43.5645) + (19.825) = Average atomic mass

63.3895 = Average atomic mass

Therefore the average atomic mass of Cu is 63.3895 atomic mass units

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-