The mass of an iron(II) sulfate crystal is 8.36 g.How many moles of FeSO4 are in the crystal?

The number of moles present in the FeSO4 are 0.055 mol.

Explanation:

The mass of a substance containing the same number  atoms in 12.0 g of 12C is known as mole. One mole of any substance is equal to  6.023 x 10^23. The moles of a substance can be determined by using the formula,

                 Number of moles = mass in grams / molecular mass

Given,

    mass = 8.36 g,

    molecular mass of FeSO4 = 151.908 g / mol

         number of moles = 8.36 / 151.908

                                       = 0.055 mol.

Explanation:

An element just has one-type atoms/atom (e.g. O2). Meanwhile, a compound is a variety of atoms (e.g. H2O).