Which statements about K2Cr2O7 as an oxidant in acidic medium are correct?

It can be used as a primary standard because it is stable and obtainable in high purity.

Its colour change (orange to green) is not a sharp end point, so a redox indicator such as diphenylamine is used.

Its equivalent mass is one-third of its molar mass.

It can be used as a primary standard because it is stable and obtainable in high purity.

Its colour change (orange to green) is not a sharp end point, so a redox indicator such as diphenylamine is used.

JEE Main levelOne or more correct optionsDifficulty 2 of 3eq194

Which statements about $K X_{2} Cr X_{2} O X_{7}$ as an oxidant in acidic medium are correct?

AIts equivalent mass is one-third of its molar mass.
BIt can be used as a primary standard because it is stable and obtainable in high purity.
CIts colour change (orange to green) is not a sharp end point, so a redox indicator such as diphenylamine is used.
DThe n-factor of $K X_{2} Cr X_{2} O X_{7}$ is 6.

Potassium dichromate is a primary standard, and two Cr atoms each change

+ 6 \to + 3

, so n

= 6

and the equivalent mass is one-sixth of the molar mass. The green

Cr X^{3 +}

masks the colour change, so a redox indicator is needed.