Niels Bohr a Danish physicist received his PhD from the University of Copenhagen in 1911. He that spent a year with J.J. Thomson and Ernest Rutherford in England. In 1913, he returned to Copenhagen Where he remained for the rest of his life. In 1920 he was named Director of the Institute of theory! Physics After first World War Bohr worked energetically for peaceful uses of atomic energy recieved the first Atoms for Peace award in 1957 Bohr was awarded the Nobel Prize in Physics 1922
(a) The Angular momentum of an electron in a given stationary state can be expressed as `m_e vr =h/(2pi)`
where n=1, 2,3 ...... Thus an electron can move only in those orbits for which its angular momentum is integral multiple of h/2`pi` that is why only certain fixed orbits are alowed
(b) The radii of the stationary states are expressed as `r_n=n^2a_0` where `a_0`=52.9 pm. Thus the radius the first stationary state, called the Bohr radius, is 52.9 pm. Normally the electron in the hydrogen atom is found in this orbit (that is n =1). As n increases the value of r will increase
(c) The most important property associated with the electron`E_n=-2.18xx10^(-18)(Z^2/n^2)J` n=1,2,3
(d)it is also possible to calculate to calculate the velocities of electrons moving in these orbits by using `v_n=2.18 10^6xxZ/n`m/sec. Qualitatively the magnitude of velocity of electron increases with increase of positive charge on the nucleus and decreases with increases the value of n.
(e)Bohr's theory can also be applied to th ions containing only one electron, similar to that present it hydrogen atom. For example , `He^+ Li^(2+) , Be^(3+)` and so on.
given by the expression Ex=-218x n=1,2,3 (d) It is also possible to calculate the velocities of electrons moving in these orbits by using V 2.1810 cm/sec Qualitatively the magnitude of velocity of electron increases with increase of positive charge on the nucleus and decreases with increase the value of n (e) Bohr's theory can also be applied to the ions containing only one electron, similar to that presenti hydrogen atom For example, Help, Be and so on
Choose the correct statement

Options

A. The order of velocity is `v_1 lt v_2 lt v_3 lt v_4` (`v_n` : where n is orbit number for a given atom)
B. The order of total energy is `E_1 gt E_2 gt E_3 gtE_4` (`E_n`:where n is orbit number for a given atom)
C. The order of velocity of electron in `H, He^+, Li^+, Be^(3+)` species in second Bohr orbit is `Be^(3+) lt Li^(+2) lt He^+ lt H`
D. The order of Bohr radius is `r_1 lt r_2 lt r_3 lt r_4` (`r_n`:where n is orbit number for a given atom)