Match the following. match the items in the left column to the items in the right column. 1. the starting materials completely lose their properties to form new substances chemical change 2. a change from one state of matter to another phase change 3. a change in shape, size, or physical characteristics but remaining same substance law of constant composition 4. a pure compound consists of exactly the same elements in the exact same ratios by mass physical change 5. the smallest unit of a compound molecule

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.