Mohr s salt = (NH₄)₂Fe(SO₄)₂.6H2O = (NH₄)2SO₄.FeSO₄.12H₂O 

The redox reaction between Mohr s salt and potassium dichromate is: 

Cr₂O₇^2- + 6Fe²⁺ + H⁺ → 2Cr³+ + 6Fe³+ 7H2O 

No. of moles of Cr₂O₇^2- = 1/6 x No. of moles of Fe²⁺

                                          = 1/6 x 0.60M x 0.75L = 0.075 mole. 

Now 0.075 mole of K₂Cr₂O₇ = 0.075 mole x 294.183g/mol = 22.064g