In the following question two statements (Assertion) A and...

In the following question two statements (Assertion) A and Reason (R) are given Mark (a) if $A$ and $R$ both are correct and $R$ is the correct explanation of $\mathrm{A}$. (b) if $\mathrm{A}$ and $\mathrm{R}$ both are correct but $\mathrm{R}$ is not the correct explanation of $\mathrm{A}$. (c) $\mathrm{A}$ is true but $\mathrm{R}$ is false. (d) A is false but $\mathrm{R}$ is true. (e) $\mathrm{A}$ and $\mathrm{R}$ both are false. (A): $\mathrm{PH}_{3}$ is stronger nucleophile than $\mathrm{NH}_{3}$ : $(\mathbf{R}): \mathrm{PH}_{3}$ is stronger base than $\mathrm{NH}_{3}$ :

In the following question two statements (Assertion) A and Reason (R) are given Mark
(a) if $A$ and $R$ both are correct and $R$ is the correct explanation of $\mathrm{A}$.
(b) if $\mathrm{A}$ and $\mathrm{R}$ both are correct but $\mathrm{R}$ is not the correct explanation of $\mathrm{A}$.
(c) $\mathrm{A}$ is true but $\mathrm{R}$ is false.
(d) A is false but $\mathrm{R}$ is true.
(e) $\mathrm{A}$ and $\mathrm{R}$ both are false.
(A): $\mathrm{PH}_{3}$ is stronger nucleophile than $\mathrm{NH}_{3}$ :
$(\mathbf{R}): \mathrm{PH}_{3}$ is stronger base than $\mathrm{NH}_{3}$ :

Key Concepts

Difference Between Nucleophilicity and Basicity

Although both nucleophilicity and basicity involve the donation of electrons, they are conceptually distinct. Basicity is a thermodynamic property related to proton acceptance, while nucleophilicity is a kinetic property that governs the speed at which an electron pair donor reacts with an electrophile. Factors such as solvent effects and steric hindrance may influence one more than the other.

Periodic Trends and Atomic Properties

Periodic trends such as atomic size, electronegativity, and polarizability play a significant role in both nucleophilicity and basicity. Generally, larger and more polarizable atoms can be more effective nucleophiles due to their ability to donate electrons readily, while electronegativity influences the electron-withdrawing or donating nature of atoms, thereby affecting their tendency to act as bases.

Nucleophilicity

Nucleophilicity is the ability of a chemical species to donate a pair of electrons to an electrophile and form a new chemical bond. It is influenced by factors such as charge density, polarizability, steric hindrance, and the solvent, and is crucial in determining the reactivity of molecules in substitution and addition reactions.

Basicity

Basicity refers to the tendency of a molecule to accept a proton, usually evaluated by the pKa of its conjugate acid. This property depends on the availability of a lone pair of electrons for bonding with a proton and is affected by the molecular structure, electron donation, and the presence of substituents.

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