4. What is node and nodal plane? How many nodal planes are possible for 2p and 3d orbitals?
Ans: The point where the probability of finding electron is called nodal point or "node". The plane passing through node is called "nodal plane".
number of nodal planes = l
nodal planes for 2p = 1
nodal planes for 3d = 2
5. Explain briefly Planck's quantum theory.
Ans: Black body radiation was successfully explained by Max Planck. A hollow metallic sphere coated inside with platinum black with a fine hole acts as black body. Which is a perfect absorber and perfect radiator of energy.
→ The emission of radiation is due to vibrations of electrons in the body.
→ Radiation is associated with energy.
→ The energy is emitted or absorbed by a body discontinuously in the form of small packets called "Quantum".