2. The minimized structure of phenacetin is planar, and the chemical shifts of the aromatic protons in the NMR spectrum can be rationalized by electron delocalization. When drawn in the planar conformation, are any of the aromatic protons related by a valid symmetry operation? Explain why the resonances in the aromatic region produce two doublets instead of more complex splitting patterns.

Explanation:

Reason for the aromatic region shows two doublets:

1. Two types of protons present in the aromatic ring (Ha & Hb protons) based on their environment.

2. Two doublets are respectively shown to the two Ha protons in the ortho position and the two Hb protons in the meta position from the amide group.

3. Two Ha protons are coupled with two Hb protons.  

Summary: Two sets (Ha & Hb) of two equivalent protons (4 protons) present in the aromatic ring of Phenacetin. Two Ha protons are coupled with two Hb protons hence in the aromatic region two doublets are observed,

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.