How many moles are in 123.0 grams of KClO4? (3 points) 0.2354 mol KClO4
0.6445 mol KClO4
0.7124 mol KClO4
0.8878 mol KClO4

0.8878 mol KClO4

Explanation:

Molar mass of KClO4 = 39.0983 + 35.453 + ( 15.9994 x 4 ) = 39.0983 + 35.453 + 63.9976 = 138.5489g/mol

but,

number of moles = mass in grams / molar mass where mass in grams = 123g, molar mass = 138.5489g/mol

number of moles = 123g / 138.5489g/mol = 0.8878mol

  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-