Not considering the electronic spin, the degeneracy of the second excited state( n = 3) of H atom is 9, while the degeneracy of the second excited state of H^– is ___________.

In an atom, the total number of electrons having quantum numbers n = 4, |m_l| = 1 and m_s = –1/2 is

The atomic masses of He and Ne are 4 and 20 a.m.u., respectively. The value of the de Broglie wavelength of He gas at –73^oC is “M” times that of the de Broglie wavelength of Ne at 727^oC. M is

The maximum number of electrons that can have principal quantum number, n = 3, and spin quantum number, m_s = − 1/2 , is