KVPY Interview Important Questions Chemistry Part 1

1. Explain Bohr Theory model of Atom

Sol. BOHR’S Atomic Model

Bohr’s model is applied only on one electron species like H, Equation , Equation etc.

The important postulates of Bohr model of an atom are

(A) Electron revolves around the nucleus in a fixed circular orbit of definite energy. As long as the electron occupy a definite energy level, it does not radiate out energy i.e. it does not lose or gain energy. These orbits are called stationary orbits

(B) Electron revolves only in those orbits whose angular momentum Equation is an integral multiple of the factor Equation (where ‘h’ is Plank’s constant)



m = mass of the electron

v= velocity of the electron

n= number of orbit in which electron revolves

r = radius of the orbit

(C) The energy is emitted or absorbed only when the electron jumps from one energy level to another. It may jump from higher energy level to a lower level by the emission of energy and jump from lower to higher energy level by absorption of energy.

This amount of energy emitted or absorbed is given by the difference of the energies of the two energies of the two energy levels concerned

Q: 2. How would you derive the energy of electron orbit of Hydrogen atom? Show proper derivation

Sol. The total energy of an electron revolving in a particular orbit is


Where: P.E. = Potential energy, K.E. = Kinetic energy, T.E. = Total energy

The Equation of an electron Equation

And the P.E. of an electron Equation

Hence, T.E. Equation

We know that, Equation

Substituting the value of Equation in the above equation:


So, T.E. Equation

Substituting the value of ‘r’ in the equation of T.E.

Then Equation

Putting the value of m, e, h and π we get the expression of total energy


Q: 3. Which institute you like to join in future?

Sol. Resonance

Q: 4. Draw the shape of Equation orbital with proper sign of orbital wave function

Sol: The wave function for Equation has maximum amplitude along z-axis. It is zero along Equation plane. Similarly Equation has maximum probability of finding electron along x and y-axis.

Contour diagram for 2p-orbitals are shown in the figure given

Q: 5. What is carbine?

Sol. Carbon is a reaction intermediate in which one of the carbon is uncharged but electron deficient. It has only 6-valene Equation . Such an intermediate is highly reactive


Q: 6. Give two methods to generate carbine?


1. Chloroform with KOH gives dichloro carbine

2. Diazomethane with light or heat gives carbine

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