Question

what combination of rings and multiple bonds can occur in a compond with the molecular formula C7H8O?

A) 3 double bonds

B) 2 rings, 1 double bond and 1 triple bond

C) 2 rings and 3 double bond

D) 1 ring and 2 double bond

E) 2 triple bonds

And then (Please explain the possible combinations of rings/bonds for 1,2,3 and 4 degrees)

Answer 1

degree of unsaturation = (2C +2 +N - X - H) / 2
dou = (2*7 + 2 - 8) / 2 = 4
Option E ,2 triple bonds can occur
Always remember these 2 conditions,
1) One degree of unsaturation is equivalent to 1 ring or 1 double bond .
2) Two degrees of unsaturation is equivalent to 2 double bonds, 1 ring and 1 double bond, 2 rings, or 1 triple bond   
For duo = 1 , 1 double bond or ring can occur
For duo =2 , 1 double bond +1 ring , 2 double bonds / 2 rings , 1 triple bond can occur
For duo =3 , 3 rings, 2 rings+1 double bond, 1 ring+2 double bonds, 1 ring+1 triple bond,
1 double bond+1 triple bond, or 3 double bonds.
For duo=4 , 4 double bonds/4 rings , 2 double bonds+2 rings , 3 double bond+1 ring, 1 double bond + 3 rings
2 triple bonds , 1 triple bond+1ring+1double bond, 1 triple bond+2rings , 1 triple bond+2double bonds