$Na_2B_4O_7 \cdot 10H_2O \xrightarrow{\Delta} 2NaBO_2 + B_2O_3 (A) + 10H_2O$. $(A) + MnO \xrightarrow{\Delta} Mn(BO_2)_2 (B)$. $(A)$ and $(B)$ are

Discuss the pattern of variation in the oxidation states of $(i)$ $B$ to $Tl$ and $(ii)$ $C$ to $Pb$.

In the following reaction,assign the state for the underlined atom in the product of complete hydrolysis at $R.T.$:
$H_4\underline{P}_2O_7 + H_2O \longrightarrow 2H_3PO_4$

In the following sets of reactants,which two sets best exhibit the amphoteric character of $Al_2O_3 \cdot xH_2O$?
Set $1$: $Al_2O_3 \cdot xH_2O_{(s)}$ and $OH^{-}_{(aq)}$
Set $2$: $Al_2O_3 \cdot xH_2O_{(s)}$ and $H_2O_{(l)}$
Set $3$: $Al_2O_3 \cdot xH_2O_{(s)}$ and $H^{+}_{(aq)}$
Set $4$: $Al_2O_3 \cdot xH_2O_{(s)}$ and $NH_{3(aq)}$

Which of the following statements is incorrect?

Anhydrous aluminium chloride fumes in moist air owing to the formation of