Which of these is true of a chemical reaction? (a) The total number of atoms does not change, so mass is conserved in the reaction. (b) Even if the total number of atoms changes, mass may not be conserved in the reaction. (c) Even if the total number of does not change, mass may not be conserved in the reaction. (d) The total number of atoms changes, so mass is conserved in the reaction.

law of conservation of matter

it is the most commonly accepted one

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.