Which of the statements is not true?

$\displaystyle \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution in acidic medium is orange.

$\displaystyle \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution becomes yellow on increasing the pH beyond $\displaystyle 7$

On passing $\displaystyle \mathrm{H}_2 \mathrm{~S}$ through acidified $\displaystyle \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution, a milky colour is observed.

$\displaystyle \mathrm{Na}_2 \mathrm{Cr}_2 \mathrm{O}_7$ is preferred over $\displaystyle \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ in volumetric analysis.