Number of unpaired electrons in 1s² 2s² 2p³ is -

1. 2

2. 0

3. 3

4. 1

The quantum numbers of four electrons are given below.

                                  n            $\mathcal{l}$           m          s 

(1) Electron 1             3            0             0           -1/2

(2) Electron 2             4            0             0           1/2

(3) Electron 3            3             2             0           1/2

(4) Electron 4            3             1             0           -1/2

The correct order of decreasing energy of these electrons is - 

1. Electron 3 > Electron 1 > Electron 4> Electron 2

2. Electron 4> Electron 2 > Electron 3 > Electron 1

3. Electron 3 > Electron 2 > Electron 4 > Electron 1

4. Electron 2 > Electron 4 > Electron 3 > Electron 1

Which type of radiation is not emitted by the electronic structure of atoms:

1. Ultraviolet light

2. X-rays

3. Visible light

4. y-rays

An absorption line of the lowest frequency in the transition of hydrogen spectra is

1. n=1 to n=2

2. n=3 to n=8

3. n=2 to n=1

4. n=8 to n=3

If uncertainty in the position of an electron is zero the uncertainty in its momentum will be: 

1. <h/4$\mathrm{\pi }$

2. >h/4$\mathrm{\pi }$

3. zero

4. infinite

The maximum number of atomic orbitals associated with a principal quantum number 5 is-

1. 9

2. 12

3. 16

4. 25

The de Broglie wavelength of electron of He⁺ ion is 3.329Å. If the photon emitted upon de-excitation of this He⁺ ion is made to hit H atom in its ground state so as to liberate electron from it, what will be the de Broglie's wavelength of photoelectron ?

1. 0.1518 Å

2. 6.1518 Å

3. 2.3518 Å

4. 4.1218 Å

Velocity of helium atom at 300 K is 2.40 x 10² meter per sec. What is its wavelength? (mass number of helium is 4) -

1. 0.416 nm

2. 0.83 nm

3. 803 Å

4. 8000 Å

The de-Broglie wavelength of a particle having the momentum of
3.3 x 10^-24 kg m s^-1 will be;

1. 0.002 Å

2. 0.02 Å

3. 0.2 Å

4. 2Å

Which of the following statements is not true with respect to photoelectric effect -

1. The plot of kinetic energy of the photoelectrons against frequency of absorbed radiation gives a straight line parallel to x-axis

2. The plot of K.E. of the photoelectrons against frequency of absorbed radiation gives a straight line with slope equal to h and intercept to work function of metal

3. The plot of kinetic energy of the photoelectrons versus the intensity of incident radiation with constant frequency gives a straight line parallel to x-axis

4. When intensity of light is increased the number of photons ejected increases but the energies of these electrons are the same.