Umm care to help, please

17.5

Explanation:

20

Explanation:

Protons (the atomic number) and neutrons both contribute to the atomic mass.

If you therefore subtract the number of protons (19) from the atomic mass (39), you are left with the number of neutrons (=20).

hope this helped :)

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.