Question

How many different type of protons are prwsent in allyl bromide?

Answer 1

If the proton has two types of neighboring protons then number of lines is equal to (n1 + 1) (n2 + 1). For example in 3-bromopropene or allyl bromide (Br-CH2-CH=CH2), the H on C2has three different protons so it is coupled by three different coupling constant.