A sample of a pure element has a mass of 45.6g and contains 4.19 x 10 23 atoms. Identify the element.

    ZINC

To identify the element based on the informartion given, we have to find the molar mass since this mass is unique to each element.

            Molar mass = mass ÷ moles

We already know the mass based on the question, as such we now need to find the # of moles.

           Since 1 mole contains 6.02214 × 10²³ atoms

      then let  x moles contain 4.19 × 10²³ atoms (given in the question)

      ⇒   x =  (4.19 × 10²³ atoms  ×  1 mol) ÷ 6.02214 × 10²³ atoms

              x  =  0.69577 mol

Now that we have the moles we can substitute it into the molar mass equation and solve for the molar mass.

           ⇒ molar mass = 45.6 g ÷ 0.69577 mol

           ⇒ molar mass ≈  65.54 g/mol

                    This molar mass is closest to that of ZINC.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).