Q 1 :    

The value of Rydberg constant (RH) is 2.18×10-18 J. The velocity of electron having mass 9.1×10-31 kg in Bohr's first orbit of hydrogen atom = _____ ×105ms-1 (nearest integer)                    [2024]



(22)             Velocity (v) of electron in nth Bohr orbit of a single electron specie with atomic no. Z is given by:

                     ν=2.18×108Zncm/s

                     For hydrogen atom, Z = 1 and for first orbit n = 1.

                     ν=2.18×108×11cm/s=2.18×106m/s22×105m/s



Q 2 :    

For hydrogen atom, energy of an electron in first excited state is -3.4 eV, K.E. of the same electron of hydrogen atom is x eV. Value of x is _________ ×10-1 eV. (Nearest integer)                  [2024]



(34)               For an electron present in a single electron species in any of the orbits,

                      Total energy : kinetic energy : potential energy = -1 : +1 : -2

                       Thus if total energy is -3.4 eV, then kinetic energy is +3.4 eV = 34×10-1 eV.



Q 3 :    

Radius of the first excited state of Helium ion is given as: a0 radius of first stationary state of hydrogen atom.             [2025]

  • r=2a0

     

  • r=4a0

     

  • r=a02

     

  • r=a04

     

(1)

r=a0n2Z

For He+ ion, Z = 2 and for first excited state, n = 2.

r=a0222=2a0



Q 4 :    

For hydrogen like species, which of the following graphs provides the most appropriate representation of E vs Z plot for a constant n ?

[E : Energy of the stationary state, Z : atomic number, n : principal quantum number]                  [2025]

  •  

  •  

  •  

  •  

(4)

E=-2.18×10-18(Z2n2)J

 



Q 5 :    

According to Bohr’s model of hydrogen atom, which of the following statement is incorrect?           [2025]

  • Radius of 3rd orbit is nine times larger than that of 1st orbit.

     

  • Radius of 8th orbit is four times larger than that of 4th orbit.

     

  • Radius of 6th orbit is three times larger than that of 4th orbit.

     

  • Radius of 4th orbit is four times larger than that of 2nd orbit.

     

(3)

Radius (r) of nth shell of a single electron specie with atomic number Z is given by:

r=52.9n2Zpm

Thus, r6r4=6242=94

 



Q 6 :    

The energy of an electron in first Bohr orbit of H-atom is –13.6 eV. The magnitude of energy value of electron in the first excited state of Be3+ is ______ eV. (nearest integer value)        [2025]



(54)

E=-13.6Z2n2eV

For Be3+, Z = 4. For first excited state, n = 2.

E=-13.64222eV=-54.4eV