Just a small note to the answer for H3 tutorial qns on NMR

This is another FAQ. Many students ask, are the two protons on the =CH2 of the terminal alkene equivalent or not?

The answer is, it depends.
1) if the two groups on the other carbon are not the same, then the two protons are non equivalent. eg CH3CH=CH2. the two protons on CH2 are not equivalent

2) if the two grops on the other carbon are the same, then there is symmetry and the two protons are equivalent.
eg. (CH3)2C=CH2.
this is the case for one of the tutorial qns

3) sometimes the NMR spectrometer has a poor resolution and cannot differentiate the slight difference in the two protons in the =CH2 group. This is the case for some of the spectra you get to read!

so lets say for CH3CH=CH2, if you were to asked predict, you should predict 4 signals. a doublet of intensity 3 from CH3, a multiplet of intensity 1 from the CH, and another 2 doublets each of intensity 1 from the two CH2 protons(ie one doublet from each proton)

but when you read from the spectrum, you may possibly get the two CH2 protons giving the same signal, ie a doublet with intensity 2. so thats a total of only 3 signals.

you get the drift right?