Consider four elements from Group 17: fluorine in the second period, chlorine in the third period, bromine in the fourth period, and iodine in the fifth period. Which element has the largest first ionization energy? A. fluorine B. chlorine C. bromine D. iodine E. You need more data to predict the first ionization energy of these elements.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.