Which of the following statements about n-factors is/are correct?

AThe n-factor of $Na X_{2} S X_{2} O X_{3}$ when it is converted to $Na X_{2} S X_{4} O X_{6}$ is 2.
BThe n-factor of $H X_{3} PO X_{3}$ in complete neutralisation by $NaOH$ is 2.
CThe n-factor of $KMnO X_{4}$ is 1 when it is reduced to $K X_{2} MnO X_{4}$ in strongly basic medium.
DThe n-factor of $H X_{3} PO X_{2}$ acting as an acid towards $NaOH$ is 1.

Answer: B, C, D

H X_{3} PO X_{3}

is dibasic (n = 2) and

H X_{3} PO X_{2}

is monobasic (n = 1). Reduction of

MnO X_{4} X^{-}

MnO X_{4} X^{2 -}

is a one-electron change (n = 1). Two thiosulphate ions together lose 2 electrons to give

S X_{4} O X_{6} X^{2 -}

, so n for

Na X_{2} S X_{2} O X_{3}

is 1, not 2.