State the number of hydrogens bonded to each labeled carbon in the following substance and give its molecular formula.

$($The molecular formula answer is case$-$sensitive$.$ The order of atoms should be carbon, then hydrogen, then others in alphabetical order.$)$

a$.$ Hydrogens at carbon a

b$.$ Hydrogens at carbon b $0$v

c$.$ Hydrogens at carbon c $0vv$

The molecular formula is