# Which of the following is metaboric acid ?

$\begin {array} {1 1} (A)\;HBO_2 & \quad (B)\;H_3BO_3 \\ (C)\;H_2B_4O_7 & \quad (D)\;B_2O_3 \end {array}$

Metaboric acid is formed by heating of boric acid.
$H_3BO_3 \large\frac{375k}{-H_2O}$$HBO_2$
Hence option (A) is the correct answer.
$HBO_2$
edited Mar 26