Phosphorus has an atomic number of 15, so what is the distribution of its electrons in an uncharged atom?a. The first energy level has two, the second has eight, and the third has five. b. The electron arrangement cannot be determined from the atomic number alone. c. The first energy level has eight and the second has seven. d. The first energy level has two and the second has 13. e. The first, second, and third energy levels have five electrons each.

a. The first energy level has two, the second has eight, and the third has five.      

Explanation:

In the periodic table , all of the elements are arranged according to the atomic number , the phosphorus is groups at position 15 and hence the atomic number is 15 .

The electrons of the elements are arranged according to the stability of the electrons , which is decided by the octet rule , where the stable electronic configuration is - 2 , 8 , 8 , 18...

i.e. ,

In the first shell maximum two electrons can reside , and in the second shell , maximum eight electrons can reside ,and so on.

Hence , determining the electron configuration as follows -

P ( 15 ) - 2 , 8 , 5 .