Total Weight - Container weight = Liquid Weight
1300 - 250 = 1050 / 1.05 = 1000 (amount filled in the container)
So
1050 g
The weight of each g/ml must be 1.05 in order to get 1050 ml.
The answer is 1.05
( Credit given to user "Aakasha A.', information above used only to pass on information that has been answered already )
