1.0 mole of ethyl alcohol and 1.0 mole of acetic acid are mixed. At equilibrium, 0.666 mole of ester is formed. The value of equilibrium constant is

1 mole of C2H5OH react with 1 mole of CH3COOH gives 1 mole of CH3COOC2H5 and 1 mole of H2O'X1' mole of C2H5OH react with 'X2' mole of CH3COOH gives 0.666 mole of COOC2H5 and X3 moles of H2OX1 = X2 = X3 = 0.666