Question

With greater deshielding, the effective magnetic field felt by the proton increases, and the chemical shift of its signal ________.

A) Decreases
B) Increases
C) Remains Constant
D) Becomes Variable

Answer 1

With greater deshielding, the effective magnetic field at the nucleus increases, resulting in an increased chemical shift (downfield) in the NMR spectrum. The correct option is B).

Step-by-step explanation:

With greater deshielding, the effective magnetic field felt by the proton increases, and the chemical shift of its signal increases (B).

Deshielding refers to the reduction in the electron density around a nucleus (like a proton), which can be caused by electronegative atoms or pi systems that pull electron density away from the nucleus.

This makes the nucleus feel a greater local magnetic field and thus, shifts the absorption to a higher frequency (downfield) in Nuclear Magnetic Resonance (NMR) spectroscopy. The further downfield (to the left on the NMR spectrum), the greater the chemical shift. Option B) is the correct one.