the answer he chemical reaction CrF3+H3PO4 → CrPO4 + 3HF the main formula is when we observe a reaction as follow: XY + ZT --------------- XT + YZ this is classified as double replacement reactions, this means: two ionic compounds exchange ions, producing 2 new ionic compounds. in our case we have CrF3+H3PO4 → CrPO4 + 3HF so the classification is double-replacement reactions
