Compound Y+ K2Cr2O7 ---> C6H12O2

What is compound Y?

compound X is CH3CH2CH2CH2CH2COOH

Y is CH3CH2CH2CH2CH2CHO = C6H12O
Y is the aldehyde and X is the acid. Aldehydes are oxidized witrh dichromate to carboxylic acids.
In general RCHO ==> RCO2H