methanoic acid react with potassium dichromate to form what?

A colorless solution and CO2 is formed as known

1 answer

CO2 and H2O are the products of the oxidation of HCOOH.
The K2Cr2O7 will be reduced to Cr^+3, which is green, which doesn't agree with your statement about a colorless solution being formed. Water is colorless, of course, but the solution, which is the water + Cr(III) ion, is green.