Calculate the wavelength in Angstrom of the photon that is emitted when an electron in the Bohr orbit, n = 2 returns to the orbit, n = 1 in the hydrogen atom. The ionization potential of the ground state hydrogen atom is 2.17 $$\times$$ 10^-11 erg per atom.

The energy released when an electron is added to a neutral gaseous atom is called ______ of the atom.

The compound with no dipole moment is

There are ______ $$\pi$$ bonds in a nitrogen molecule.