When beryllium is bombarded with $\alpha$-particles, extremely penetrating radiations are produced which cannot be deflected by electrical or magnetic fields. These are:

1. Protons

2. $\alpha$ -rays

3. Neutrons

4. X-rays

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

The sub-shell that comes after f-sub-sell is called g-subshell. The number of g-sub orbitals in g-sub-shell and the total number of orbitals in the principal orbital respectively are-

1. 10 and 25

2. 9 and 25

3. 11 and 23

4. 15 and 45

The wavelengths of two photons are 2000 Å and 4000 Å respectively. What is the ratio of their energies?

1. 1/4

2. 4

3. 1/2

4. 2

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

The number of electrons in one molecule of CO₂ are - 

1. 22

2. 44

3. 66

4. 88

The ion that is isoelectronic with CO is-

1. CN^-

2. O₂⁺

3. O₂^-

4. N₂⁺

If frequency of the X-rays produced using an element as anti-cathode is found to be 2500 sec^-1, the atomic number of used element is (a, b= 1)

1. 51

2. 49

3. 56

4. 72

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