## Class 11 - Chemistry

**Question:**

Write the electronic configuration and number of unpaired electrons in Fe^{2+}ion.

**Answer:**

Fe (Z = 26) : [Ar]^{18} 3d^{6}4s^{2}

Fe^{2+}ion : [Ar]^{18} 3d^{6}

No. of unpaired electrons = 4

## Questions and Answers

**Structure of Atom**- Questions

An electron beam on hitting a ZnS screen produces a scientillation on it. What do you conclude?

With what velocity must an electron travel so that its momentum is equal to that of a photon of wavelength = 5200 A?

Using Aufbau principle, write the ground state electronic configuration of following atoms.

(i)Boron (Z = 5) (ii) Neon (Z = 10), (iii) Aluminium (Z = 13) (iv) Chlorine (Z = 17), (v) Calcium (Z = 20) (vi) Rubidium (Z = 37)

The kinetic energy of an electron is 4.55 x 10^{-25} J. The mass of electron 9.1 x 10^{-1} kg. Calculate velocity, momentum and the wavelength of the electron?(Haryana Board, 2004, AII CBSE 2000)

What are the two longest wavelength lines (in manometers) in the Lyman series of hydrogen spectrum?

State and explain the following:

(i) Aufbau principle

(ii) Pauli exclusion principle.

(iii) Hund’s rule of maximum multiplicity.

Arrange s, p and d sub-shells of a shell in the increasing order of effective nuclear charge (Z_{eff}) experienced by the electron present in them

An atom having atomic mass number 13 has 7 neutrons. What is the atomic number of the atom?

An electron beam after hitting a neutral crystal produces a diffraction pattern? What do you conclude?

In a hydrogen atom, the energy of an electron in first Bohr’s orbit is 13.12 x 10^{5} J mol^{-1}. What is the energy required for its excitation to Bohr’s second orbit?

What were the weaknesses or limitations of Bohr’s model of atoms ? Briefly describe the quantum mechanical model of atom.

Giue flic name and atomic number of the inert gas atom in which the total number of d-electrons is equal to the difference between the numbers of total p and total s-electrons.

Arrange the electron (e), protons (p) and alpha particle (Î±) in the increasing order for the values of e/m (charge/mass).

Show the distribution of electrons in oxygen atom (atomic number 8) using orbital diagram.

Show the distribution of electrons in oxygen atom (atomic number 8) using orbital diagram.

Which of the following will not show deflection from the path on passing through an electric field?

Proton, cathode rays, electron, neutron.

Give the relation between wavelength and momentum of moving microscopic particle. What is the relation known as?

The uncertainty in the position and velocity of a particle are 10^{-10}m and 5.27 x 10^{-24} ms^{-1} respectively. Calculate the mass of the particle. (Haryana Board 2000)

(a) What is the limitations of Rutherford model of atoms?

(b) How has Bohr’s theory helped in calculating the energy of hydrogen electron in different energy levels?

The electronic configuration of valence shell of Cu is 3d^{10} 4s^{ 1} and not 3d^{9}4s^{2}. How is this configuration explained?

The Balmer series in the hydrogen spectrum corresponds to the transition from n_{1} = 2 to n_{2} = 3, 4,……… This series lies in the visible region. Calculate the wave number of line associated with the transition in Balmer series when the electron moves to n = 4 orbit. (R_{H} = 109677 cm^{-1}).

The uncertainty in the position of a moving bullet of mass 10 g is 10^{-5 }^{ }m. Calculate the uncertainty in its velocity?

Which of the following orbitals are degenerate?

3d_{xy}, 4d_{xv}, 3d_{yz}, 3d_{z}^{2}_{:}, 4d_{yz}., 4dz^{2}_{:}