The quantum number of four electrons are given below :
n = 4, l = 2, m_l =–2, m_s = –1/2
n = 3, l = 2, m_l = 1, m_s = +1/2
n = 4, l = 1, m_l = 0, m_s = +1/2
n = 3, l = 1, m_l = 1, m_s = –1/2
The correct order of their increasing enegies will be :

If the de Broglie wavelength of the electron in n^th Bohr orbit in a hydrogenic atom is equal to 1.5 $$\pi $$a₀ (a₀ is Bohr radius), then the value of n/z is -

The upper stratosphere consisting of the ozone layer protects us from sun's radiation that falls in the wavelength region of -

What is the work function of the metal if the light of wavelength 4000$$\mathop A\limits^ \circ $$ generates photoelectrons of velocity 6 $$ \times $$ 10⁵ ms^–1 from it ?
(Mass of electron = 9 $$ \times $$ 10^–31 kg;
Velocity of light = 3 $$ \times $$ 10⁸ ms^$$-$$1
Plank's constant = 6.626 $$ \times $$ 10^–34 Js;
Charge of electron = 1.6 $$ \times $$10^–19 JeV^–1)