Determine the number of atoms in 1.75 ml of mercury. (the density of mercury is 13.5 g/ml.)

The number  of atoms in 1.75 ml of mercury is 7.1036 x10^22 atoms

calculation

find mass of Hg= M xV

=1.75 ml x 13.5 g/ml =23.625 grams

find the number of moles of Hg =mass/molar mass

moles= 23.625g/200.56g/mol=0.118 moles

by use of Avogadro law that is 1 mole= 6.02 x10^23 atoms

0.118 moles=? atoms

by cross multiplication

=(0.118 moles x6.02 x10^23atoms) /1 mole= 7.091 x10^22 atoms

  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-

58750.08068 is the answer i think