Science People Pleasee HEL a)In the original periodic table proposed by Mendeleev, the elements were arranged in order of a certain property. State that property.

b) In the modern periodic table, the elements are arranged in order of another property. State that property.

c) Write a sentence or two explaining how Mendeleev was able to come up with a periodic table that is close to the modern periodic table when he used the “wrong” property to arrange the elements. [Hint: Are the two properties related in any way?]

  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-