Stoichiometry (8A. S, 8B. R, 8G. S, 8H. S]:Question 4
What is the mass of 1.204 x1024 particles of Li2O?

                    59.76 grams of Li₂O

Explanation:

To solve this problem we will first calculate the moles of Li₂O.                       One mole of given substance always contains 6.022 × 10²³ particles  which can be atoms, ions, molecules or formula units. This number is also called as Avogadro's Number.

The relation between Moles, Number of Particles and Avogadro's Number is given as,

                         Number of Moles  =  Number of Particles ÷ 6.022 × 10²³

Putting values,

                         Number of Moles  =  1.204 × 10²⁴ Particles ÷ 6.022 × 10²³

                         Number of Moles  =  2.0 Moles

Secondly, we will convert calculated moles to mass using following relationship.

                         Moles  =  Mass  /  M.Mass

Or,

                         Mass  =  Moles  ×  M.Mass

Putting values,

                         Mass  =  2.0 mol × 29.88 g/mol

                         Mass  =  59.76 grams of Li₂O

  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-

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be