The correct observation in the following reactions is :

The heat of combustion of ethanol into carbon dioxide and water is – 327 kcal at constant pressure. The heat evolved (in cal) at constant volume and 27^oC (if all gases behave ideally) is (R = 2 cal mol^–1 K^–1) ________.

For the disproportionation reaction
2Cu⁺(aq) ⇌ Cu(s) + Cu²⁺(aq) at 298 K. ln K
(where K is the equilibrium constant) is
___________ × 10^–1.
Given :
($$E_{C{u^{2 + }}/C{u^ + }}^0 = 0.16V$$
$$E_{C{u^ + }/Cu}^0 = 0.52V$$
$${{RT} \over F} = 0.025$$)

The oxidation states of transition metal atoms in K₂Cr₂O₇, KMnO₄ and K₂FeO₄, respectively, are x, y and z. The sum of x, y and z is _______.