Name the most crucial enzyme found in root nudules for `N_2` fixation? Does it require a special pink coloured pigment for its functioning. Elaborate.

Name the most crucial enzyme found in root modules for nitrogen fixation.

Name the oxygen binding pigment found in root nodules of plants like bean and pea. What is the normal colour of this pigment?

Bohr's model of hydrogen atom In order to explain the stability of atom and its line spectra, Bohr gave a set of postulates: An electron in an atom revolves in certain circular orbit around the nucleus. These are the orbits for which mvr=(nh)/(2pi) In these allowed orbits, the electron does not radiate energy. When an electron jumps from higher energy level E_(n_2) to lower energy orbit E_(n_1) , radiation is emittd and frequency of emitted electron is given by v=(E_(n_2)-E_(n_1))/h . Further the radius of the n^(th) orbit of hydrogen atom is r=(n^2h^24piepsilon_0)/(4pi^2me^2) and energy of the n^(th) orbit is given by E_n=-13.6/n^2 eV . If 13.6 eV energy is required to ionise the hydrogen atom, then enegy required to remove an electron from n=2 is: