The energy of the electron in the second and the third Bohr's orbits of the hydrogen atom is -5.42 $$\times$$ 10^-12 erg and -2.41 $$\times$$ 10^-12 erg respectively. Calculate the wavelength (in Å) of the emitted radiation when the electron drops from the third to second orbit.

1 mole of N₂H₄ loses 10 moles of electrons to form a new compound Y. assuming that all nitrogen appears in the new compound , what is the oxidation state of nitrogen in Y ? (there is no change in the oxidation state of hydrogen)

If 0.50 mol of BaCl₂ is mixed with 0.20 mol of Na₃PO₄, the maximum amount of Ba₃(PO₄)₂ that can be formed is

A 1.00 gm sample of H₂O₂ solution containing X percent H₂O₂ by weight requires X ml of a KMnO₄ solution for complete oxidation under acidic conditions. Calculate the normality of the KMnO₄ solution.