Fill in the blanks

1. Every atom is a sphere of radius of the order of …………………. M

2. Atom consists of small central core, called …………………………………… in which whole mass and positive charge is assumed to be concentrated.

3. Atom is electrically……………………………………….( neutral, negative, positive)

4. At a certain distance from the nucleus, whole of the KE of α-particle converts into …………………… and α-particle cannot go further close to nucleus, this distance is called distance of closest approach.

5. Bohr’s first postulate was that an electron in an atom could revolve in ……………………… without the emission of radiant energy.

6. The angular momentum (L) of the orbiting electron is quantized, i. e  mvr =......................

7. Value of h (the Planck’s constant) is………………………………………

8. SI Unit of the Planck’s constant……………………………………
9. Bohr’s third postulate states that an electron might make a transition from one of its stable orbits to another stable orbit of lower energy. When it does so,………….. is emitted having energy equal to the energy difference between the initial and final states.

10. SI Unit of Rydberg’s constant is ………………..

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