Question

plz answer 5,6,7(ii) & 9th questions quickly

Answer 1

5 . Aufbau principle and hund's rule 

6.Na :

 1s2 => n = 1 l= 0 m=0 s = +/- 1/2

2s2 => n=2 l=0 m= 0 s = +/- 1/2

2p6 => n = 2 ; l = 1 , m = -1 , 0 , +1 s = +/- 1/2

3s1 => n = 3 l=0 m=0 s = + 1/2

Similarly you can found the quantum numbers for As 

The principal quantum number (n) describes the size of the orbital.

The angular quantum number (l) describes the shape of the orbital.

the magnetic quantum number (m), to describe the orientation in space of a particular orbital

the spin quantum number is a quantum number that parameterizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle.

n = 2 principle shell 
l = 0 , means it lies in s - orbital 
m = 0 means either it is in 1s or 2s or 3s 
s = + 1/2 it represent the direction or spin 
then orbital = 2s 

1s1 for As n = 1 , l = 0 , m = 0  , s = +-1/2

9 ⇒ wavelength = 1m 

as c = λυ
3 x 10⁸ = 1 x υ

υ = 3 x 10⁸ seconds