According to Hund's rule, the lowest (ground) state of the silicon atom ___.a. has 2 unpaired electrons b. has four different orbitals less than fully occupied c. has three sets of paired valence electrons d. has four unpaired electrons

Option (a) is the correct answer.

Explanation:

According to Hund's rule, each orbital of a sub-shell is occupied by a single electron first even before it is occupied by two electrons in the same orbital. And, all the electrons in singly occupied orbitals tend to have same spin.

Atomic number of silicon is 14 and its electronic configuration is . This means that there are two electrons present in its valence shell which have same spin.

Thus, we can conclude that according to Hund's rule, the lowest (ground) state of the silicon atom has 2 unpaired electrons.

the answer is either b or c

a electronegativity decreases beacuse the size of nucleus is bigger.