Take the reaction: NH3(g) + O2(g) →NO(g) + H2O(- i.
Write a balanced equation.
4 NH₃ (g) + 5O2 (g) → 4 NO (g) + 6H₂O
Identify the excess reagent, as well as how many grams of the excess reagent will remain when the reaction reaches completion provided 2.5g of each reagent was present at the beginning

explanation:

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.