Question

Choose the weak monobasic acid, among the following

• A. $H_3BO_3$
• B. $H_3PO_3$
• C. $H_3PO_4$
• D. $HNO_3$

Answer 1

Answer: (A)

$H_3BO_3$

Answer 2

$H _{3} BO _{3}$ is a weak Lewis monobasic acid, because it can only accept a pair of electron. None of its hydrogens are ionisable.

Note $H _{3} PO _{3}$ is a dibasic acid, $H _{3} PO _{4}$ is a tribasic acid, $HNO _{3}$ is a strong monobasic acid and $H _{4} P _{2} O _{7}$ is a tetrabasic acid.