What is the mass of ammonium nitrate in 250 ml of a 75% by mass solution (density = 1.725 g/ml)?

1) We need to find mass of the solution

m=D*V
D= 1.725 g/mL
V= 250 mL
m=1.725 g/mL*250 mL= 431.25 g

2) 75% = 0.75
0.75*431.25 ≈ 323 g of NH4NO3

Yes it would be a physical change.

Cause its being chemically applied?