Hydrogen fluoride is used:

a. in the manufacture of steel.
b. in the synthesis of cryolite for aluminum production.
c. as an oxidizing agent.
d. as a disinfectant.
e. as a mouthwash.

The correct answer is option B)

in the synthesis of cryolite for aluminum production.

Explanation:

Hydrogen fluoride (HF) is used in synthesis of cryolite for aluminum production.

HF is a gas that dissolves in water to form hydrofluoric acid. However, HF also react with halogenated alkanes like trichloromethane CHCl3 to form organofluorine compounds that serves as precursors in the synthesis of cryolite, an Ore from which aluminum is produced

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.

two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.