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.

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

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)

Balance the following Equations:

(i) Cu₂O + H⁺ + $$NO_3^ - \to $$ Cu²⁺ + NO + H₂O

(ii) K₄[Fe(CN)₆] + H₂SO₄ + H₂O $$\to$$ K₂SO₄ + FeSO₄ + (NH₄)₂SO₄ + CO

(iii) C2H5OH + I₂ + OH^- $$\to$$ CHI₃ + $$HCO_3^-$$ + I^- + 4H₂O