AIIMS2003Chemistryd and f Block Elements
Assertion : Solution of Na ₂ CrO ₄ in water is coloured. Reason: Oxidation state of Cr in Na ₂ CrO ₄ is +6 .
Options
- AIf both assertion and reason are true and the reason is the correct explanation of the assertion
- BIf both assertion and reason are true and the reason is not the correct explanation of the assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
B. If both assertion and reason are true and the reason is not the correct explanation of the assertion
Step-by-step solution
Na ₂ CrO ₄ solution in water is yellow in colour, when acidified changes to orange colour (due to the formation of Cr ₂ O ₇²⁻ ions). Na ₂ CrO ₄+ H ₂ SO ₄ Na ₂ Cr ₂ O ₇+ Na ₂ SO ₄+ H ₂ O Oxidation state : Na ₂ CrO ₄ Let oxidation state of Cr be x . 2(+1)+x+4(-2)=0 x=+6 .