To find the antonym (विलोम शब्द) of the underlined word in the given sentence.

The question asks to find the antonym (विलोम शब्द) of the underlined word in the given sentence.

The sentence is: "पक्षपात करना अच्छी बात नहीं है।"
The underlined word is पक्षपात (pakshpaat).

Meaning of पक्षपात (pakshpaat):

• पक्षपात means partiality, bias, favoritism, or prejudice. It refers to showing unfair preference to one side or person over another.

Now let's examine the given options:

1. अलग (alag): This means separate, different, or distinct. This is not the antonym of partiality.
2. निष्पक्षता (nishpakshata): This means impartiality, fairness, or neutrality. This is the direct opposite of partiality.
3. खण्ड (khand): This means piece, part, or section. This is unrelated to partiality.
4. विग्रह (vigrah): This means separation, dispute, or conflict. In grammar, it refers to the breaking down of a compound word. This is not the antonym of partiality.

The antonym of "पक्षपात" (partiality) is "निष्पक्षता" (impartiality).

The final answer is $\text{निष्पक्षता}$