Write the formula for each of the following compounds, listing the elements in the order given.
a. A molecule contains four phosphorus atoms and ten oxygen atoms.
b. A molecule contains one uranium atom and six fluorine atoms.
c. A compound contains one aluminum atom for every three chlorine atoms.

i think it's letter a.

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.