KVPY Interview Important Questions Chemistry Part 1
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1. Explain Bohr Theory model of Atom
Sol. BOHR’S Atomic Model
Bohr’s model is applied only on one electron species like H, , 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 is an integral multiple of the factor (where ‘h’ is Plank’s constant)
Diagram of BOHR’S Atomic Model
Diagram of BOHR’S Atomic Model
Where:
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
Diagram of Absorbed Energy and Emitted Energy
Diagram of Absorbed Energy and Emitted Energy
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 of an electron
And the P.E. of an electron
Hence, T.E.
We know that,
Substituting the value of in the above equation:
So, T.E.
Substituting the value of ‘r’ in the equation of T.E.
Then
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 orbital with proper sign of orbital wave function
Sol: The wave function for has maximum amplitude along z-axis. It is zero along plane. Similarly has maximum probability of finding electron along x and y-axis.
Contour diagram for 2p-orbitals are shown in the figure given
Diagram of 2p-Orbitals
Diagram of 2p-Orbitals
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 . Such an intermediate is highly reactive
Example:
Structure of Dichlorocarbene
Structure of Dichlorocarbene
Q: 6. Give two methods to generate carbine?
Sol.
1. Chloroform with KOH gives dichloro carbine
Structure of Chloroform with KOH Gives Dichloro Carbine
Q 6 Sol 1 Structure of Chloroform with KOH gives Dichloro Carbine
2. Diazomethane with light or heat gives carbine
Structure of Diazomethane with Light or Heat Gives Carbine
Q 6 Sol 2 Structure of Diazomethane with light or heat gives carbine
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