`K_(2)Cr_(2)O_(7)` on heating with aqueous NaOH gives

Options

A. `Cr(OH)_(2)`
B. `Cr(OH)_(3)`
C. `CrO_(4)^(2-)`
D. `Cr^(3+)`

Answer

C

Explanation

On heating with alkalies, potassium dichromate is converted to chromate and hence the colour change form orange to yellow:
`underset("Orange")(K_(2)Cr_(2)O_(7))+2NaOHoverset(Delta)tounderset("Yellow")(2K_(2)CrO_(4))+H_(2)O`