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 _______.

The work function of sodium metal is 4.41 $$ \times $$ 10^–19 J. If photons of wavelength 300 nm are incident on the metal, the kinetic energy of the ejected electrons will be (h = 6.63 $$ \times $$ 10^–34 J s; c = 3 $$ \times $$ 10⁸ m/s) ________ × 10^–21 J.

The correct observation in the following reactions is :

The major product of the following reaction is :