[jeeks]

Here is the question.
Co(NO3)2 + K2CrO4----- ?

I started with:
Co(NO3)2 + K2CrO4----- Co2CrO4 = K(NO3)2
Then:
2Co =2NO3 +2KCrO4----Co2CrO4+2KNO3
 I don't know if chromate is soluble and where I go from here.
Please *delete me*

[english]

Chromates are insoluble.

Your cobalt chromate is solid.

Are you sure it's Co₂CrO₄?

It should be CoCrO₄.

Anyway, your net ionic equation involves cobalt cation reacting with chromate anion to from cobalt chromate.

I'll save the reaction for you to write.