Question

The molar ratio of $Cr ^{2+}$ to $Cr ^{3+}$ in a mixture of $CrSO _{4}$ and $Cr _{2}\left( SO _{4}\right)_{3}$ having equal number of in both sulphates is

• A. $1: 3$
• B. $3: 2$
• C. $2: 3$
• D. $3: 4$

Answer 1

Answer: (B)

$CrSO _{4} \rightarrow Cr ^{2+}+ SO _{4}^{2-}$

$Cr _{2}\left( SO _{4}\right)_{3} \rightarrow 2 Cr ^{3+}+3 SO _{4}^{2-}$

$Cr ^{2+} \rightarrow SO _{4}^{2-}$

$\because$ Sulphates are equal in number

$2 Cr ^{3+} \rightarrow 3 SO _{4}^{2-}$

$\therefore \frac{ Cr ^{2+}}{ Cr ^{3+}}=3: 2$