How is boron trifluoride made?

Ans : The reaction of boron oxides with hydrogen fluoride produces BF3: 

B2O3 + 6 HF  2 BF3 + 3 H2O. HF is often made in situ from sulfuric acid and fluorite (CaF2). Every year, about 2300-4500 tons of boron trifluoride are produced.