How many grams of MgBr2 are in 4.3x10^23 atoms of MgBr2??

The answer to your question is  131.43 grams of MgBr₂

Explanation:

Data

number of grams = ?

number of atoms = 4.3 x 10²³

Molecule = MgBr₂

Process

1.- Calculate the molar mass of MgBr₂

MgBr₂ = 24.3 + (79.9 x 2) = 24.3 + 159.8 = 184.1 g

2.- Use proportions to calculate the number of atoms

               184.1 g of MgBr₂ 6.023 x 10²³ atoms

                  x                       4.3 x 10²³ atoms

                            x = (4.3 x 10²³ x 184.1) / 6.023 x 10²³

                            x = 7.92 x 10²⁵ / 6.023 x 10²³

                           x = 131.43 grams

if you're asking what comes out, it's steam.