Which bond is strongest and why?
a. c=c
c=n
c=o
c=s

For this you should look at each elements' electronegativity. The closer the difference is to zero is the most covalent and strongest. Even without looking at their individual electronegativities, I know that the Carbon-Carbon bond will be the strongest. They have the same electronegativity so when you subtract them you get 0. So, your answer is A, the double bonded C2

Variables,control,conclusion and finally scientific theory