Which is the correct statement for $PH_{3}$?

Q: Which is the correct statement for $PH_{3}$?

Option 1: It is less basic than $NH_3$. Explanation for Option 1: Phosphine ($PH_3$) is indeed less basic than ammonia ($NH_3$). This is primarily due to the differences in the electronegativity and size of the central atoms, phosphorus and nitrogen, respectively. Nitrogen is more electronegative than phosphorus, which means it has a stronger tendency to attract electrons. This makes the lone pair on nitrogen in $NH_3$ more available for donation to a proton, thereby making $NH_3$ more basic. In contrast, the lone pair on phosphorus in $PH_3$ is less available for donation due to the larger size and lower electronegativity of phosphorus, resulting in $PH_3$ being less basic. Explanation for why the other options are incorrect: Option 2: It is less poisonous than $NH_3$. This statement is incorrect. $PH_3$ is actually more toxic than $NH_3$. Phosphine is a highly toxic gas and can be lethal even at low concentrations, whereas ammonia, while irritating and potentially harmful, is generally less toxic than phosphine. Option 3: Bond angle of $PH_3 > NH_3$. This statement is incorrect. The bond angle in $NH_3$ is approximately 107 degrees, while in $PH_3$, it is around 93.5 degrees. The smaller bond angle in $PH_3$ is due to the larger size of the phosphorus atom and the presence of lone pair-bond pair repulsion, which is less pronounced than in $NH_3$. Option 4: It does not show reducing properties. This statement is incorrect. $PH_3$ does exhibit reducing properties. It can act as a reducing agent, especially in reactions with oxygen or halogens, where it can be oxidized to form phosphorus oxides or halides. In conclusion, Option 1 is the correct statement as $PH_3$ is indeed less basic than $NH_3$, and the explanations provided clarify why the other options are incorrect.

Question

Accepted Answer

Option 1: It is less basic than $NH_3$.

Explanation for Option 1:
Phosphine ($PH_3$) is indeed less basic than ammonia ($NH_3$). This is primarily due to the differences in the electronegativity and size of the central atoms, phosphorus and nitrogen, respectively. Nitrogen is more electronegative than phosphorus, which means it has a stronger tendency to attract electrons. This makes the lone pair on nitrogen in $NH_3$ more available for donation to a proton, thereby making $NH_3$ more basic. In contrast, the lone pair on phosphorus in $PH_3$ is less available for donation due to the larger size and lower electronegativity of phosphorus, resulting in $PH_3$ being less basic.

Explanation for why the other options are incorrect:

Option 2: It is less poisonous than $NH_3$.
This statement is incorrect. $PH_3$ is actually more toxic than $NH_3$. Phosphine is a highly toxic gas and can be lethal even at low concentrations, whereas ammonia, while irritating and potentially harmful, is generally less toxic than phosphine.

Option 3: Bond angle of $PH_3 > NH_3$.
This statement is incorrect. The bond angle in $NH_3$ is approximately 107 degrees, while in $PH_3$, it is around 93.5 degrees. The smaller bond angle in $PH_3$ is due to the larger size of the phosphorus atom and the presence of lone pair-bond pair repulsion, which is less pronounced than in $NH_3$.

Option 4: It does not show reducing properties.
This statement is incorrect. $PH_3$ does exhibit reducing properties. It can act as a reducing agent, especially in reactions with oxygen or halogens, where it can be oxidized to form phosphorus oxides or halides.

In conclusion, Option 1 is the correct statement as $PH_3$ is indeed less basic than $NH_3$, and the explanations provided clarify why the other options are incorrect.