Consider an electron which is brought close to the nucleus of the atom from an infinite distance, the energy of the electron-nucleus system:

1. Increases

2. Decreases

3. Remains the same

4. None of these

Using arbitrary energy units we can calculate that 864 arbitrary units (a.u.) are required to transfer an electron in hydrogen atom from the most stable Bohr's orbit to the largest distance from the nucleus 

n = $\infty$   E= 0

n = 1 ;   E= -864 Arbitrary units

The energy required to transfer the electron from third Bohr's orbit to the orbit n = $\infty$will be-

1. 96 Arbitrary units

2. 192 Arbitrary units

3. 288 Arbitrary units

4. 384 Arbitrary units

Helium atom can be excited to 1s¹, 2p¹ configuration by light of 58.44 nm. The lowest excited state with configuration 1s¹, 2s¹ lies 4857 cm^-1 (1/$\mathrm{\lambda }$) below the 1s¹, 2p¹ state. What would be the average He - H bond energy so that HeH₂ could form, non-endothermically from the lowest excited singlet state of helium? Neglect any difference between $∆$G and $∆$H and take $∆$H as 218 kJ mol^-1

1. 1614 kJ mol^-1

2. 1212 kJ mol^-1

3. 912 kJ mol^-1

4. 1511 kJ mol^-1

What is the energy required per mole to excite an electron from the third to fifth Bohr orbit in hydrogen ?

1. 6.336 x 10⁶J

2. 7.122 x 10⁴J

3. 0.343 x 10⁶J

4. 9.343 x 10⁴J

The energy of electron in first Bohr's orbit of H-atom is -13.6 eV. What will be its potential energy in n = 4.

1. –13.6 eV

2. - 3.4 eV

3. -0.85 eV

4. -1.70 eV

Which of the following postulates does not belong to Bohr's model of the atom?

1. Angular momentum is an integral multiple of h/2$\mathrm{\pi }$

2. The electron stationed in the orbit is stable

3. The path of an electron is circular

4. The change in the energy levels of electron is continuous

Bohr's atomic model can explain:-

1. the spectrum of hydrogen atom only

2. the spectrum of an atom or ion containing one electron only

3. the spectrum of hydrogen molecule

4. the solar spectrum

The energy of the emitted photon when an electron in $B{e}^{3+}$ ion returns from n=2 level to the ground state is 

1. 2.616 x 10^-17J

2. 26.16 x 10^-17J

3. 261.6 x 10^-18J

4. 2616 x 10^-17J

Supposing the energy of the fourth shell for the hydrogen atom is -50a.u. (Arbitrary unit). What would be its ionization potential-

1. 50

2. 800

3. 15.4

4. 20.8

Photochemical dissociation of oxygen results in the production of two oxygen atoms, one in the ground state and one in the excited state.

O₂ $\stackrel{\mathrm{hv}}{\to }$ O→O*

The maximum wavelength () needed for this is 174 nm. If the excitation energy O→O* is 3.15 x 10^-19 J. How much energy in kJ mole^-1 is needed for the dissociation of one mole of oxygen into normal atoms in ground state?

1. 498.3 kJ mol^-1

2. 418.3 kJ mol^-1

3. 524.1 kJ mol^-1

4. 612.8 kJ mol^-1