How many atoms of chromium are in 0.86 mol of potassium chromate (k2cro4)?

Atoms of Cr in 0.86 mol of K2CrO4 = 0.86 × 6.02*10^23 = 5.177 * 10^23 atoms.

Explanation:One mol of K2CrO4 contains 6.02*10^23 molecules of K2CrO4.One K2CrO4  contains 1 atom of Cr.So 0.86 mol of K2CrO4 contain 0.86 * 6.02*10^23.Which is equal to  5.177 * 10^23 atoms.

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom