An electron, practically at rest, is initially accelerated through a potential difference of 100 volts. It then has a de Broglie wavelength=$\lambda$₁Å. It then get retarded through 19 volts and then it has wavelength $\lambda$₂ Å. A further retardation through 32 volts changes the wavelength to $\lambda$₃.

What is ($\lambda$₃-$\lambda$₂)/$\lambda$₁?

1. 20/41

2. 10/63

3. 20/63

4. 10/41

Which of the following has the maximum number of  unpaired electons-

1. Mg²⁺

2. Ti³⁺

3. V³⁺

4. Fe²⁺

The azimuthal quantum number characterizes:

1. e/m ratio of electron
2. Spin of electron
3. Angular momentum of the electron
4. Magnetic momentum of the electron

For the energy levels in an atom, which one of the following statements is correct?

1. There are seven principal electron energy levels

2. The second principal energy level can have two 'sub energy levels and contains a maximum of eight electrons

3. The energy level can have a maximum of 32 electrons

4. The 4s sub-energy level is at higher energy than the 3d sub-energy level

Arrange the following particles in increasing order of values of e/m ratio: Electron(e), proton(p), neutron(n) and α-particle(α)

1. n,p,e,α

2. n,α,p,e

3. n,p,α,e

4. e,p,n,α

The increasing order of energy of electromagnetic radiation can be represented as: 

The wavelength of the photoelectric threshold of metal is 230 nm. Determine the K.E. of photoelectron ejected from the surface by UV radiation emitted from the second-longest wavelength transition (downward) of an electron in Lyman series of the atomic spectrum of hydrogen: (Use: \(R=1.09677 \times 10^7 m^{-1}\))

1. 1.074 x 10^-18 J

2. 1.937 x 10^-18 J

3. 6.213 × 10^-18 J

4. 7.123 x 10^-10 J

Beryllium's fourth electron will have the four quantum numbers :

                         n               $\mathcal{l}$               m             s

1.                    1               0                0             1/2

2.                    1               1                1             1/2

3.                    2               0                0             -1/2

4.                    2               1                 0             +1/2

Mass of neutron is ........................times the mass of an electron-

1. 1840

2. 1480

3. 2000

4. None of the above

If the size of the first orbit of the hydrogen atom is 5.29 nm, the size of the second orbit of He⁺ is

1. 2.65 nm

2. 21.16 nm

3. 10.58 nm

4. 5.29 nm