Answer:
The answer is quartet 2.40 ppm.
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Explanation:
Solution
Multiplicity or (n+1) rule:
It helps in determination of multiplicity of an individual proton or individual types of proton which are available in the molecule.
Multiplicity =(n+1)
Thus
The non equivalent protons which are attached from adjacent atom is denoted by n.
Now because there are three non-equivalent protons are present at adjacent carbon of methylene group, hence the multiplicity of methylene hydrogen is given as follows:
The multiplicity will be the same for the two hydrogen's. thus we compute multiplicity only for one hydrogen atom stated below:
Non- equivalent = 3
Multiplicity = (3 +1)
= 4
= Quartet for 2H
A quartet for 2H indicates that the hydrogen atoms attached from the carbon, which is attached one side from a methyl group and the other side form an atom that have no any hydrogens.
Now due +I effect of carbonyl group, chemical shift value is high for these two hydrogens which is exactly at 2.40 ppm or 2.40 Quartet.
