Question

Which of the following statements is not correct for a nucleophile?
$
  {\text{A}}{\text{. Nucleophiles attack low }}{{\text{e}}^ - }{\text{ density sites}}{\text{.}} \\
  {\text{B}}{\text{. Nucleophiles are not electron seeking}} \\
  {\text{C}}{\text{. Nucleophiles is a lewis acid}}{\text{.}} \\
  {\text{D}}{\text{. Ammonia is a nucleophile}}{\text{.}} \\
 $

Answer 1

Hint:- In this question first we memorize the definition and the different properties of nucleophiles. And then cross check the given options about nucleophiles. If the option is matched with the either definition or property of nucleophiles then it is correct otherwise it is wrong.

Step-By-Step solution:
Nucleophile is a word used to refer to substances that tend to donate electron pairs to electrophiles in order to form chemical bonds with them. Any ion or molecule having an electron pair which is free or a $\pi $bond containing two electrons have the ability to behave like nucleophiles.
 Since, Nucleophiles are electron rich species so they attack on low electron density sites. Therefore, option A is correct but we have to find the incorrect statement about nucleophiles.
Since, Nucleophiles are donating the electron pairs to electrophiles in order to form chemical bonds, due to which they are not electron seeking. Therefore, option B. is also correct but we have to find the incorrect statement about nucleophiles.
Since, in Ammonia the nitrogen atom has a lone pair of electrons and three bonds with hydrogen atom. So Ammonia has a tendency to donate its lone pair i.e. it is a nucleophile. Therefore, option D. is also correct but we have to find the incorrect statement about nucleophiles.
Nucleophiles are basically the electron rich species which have the ability to donate electron pairs. Because of this electron pair donating tendency, all nucleophiles are “Lewis Base” not the “Lewis Acid”. Therefore, option C. is incorrect about “Nucleophiles”.
Hence, option C. is the correct answer.

Note:- Whenever you get this type of question the key concept to solve this is to learn the definition of the terms involved in the question like in this question we have to learn the definition and properties of nucleophiles. And one more thing to be remembered is that a lone pair of electrons occupying an orbital in an atom or molecule is not directly involved in the bonding.