This question involves predicting the major nitration products for three aromatic compounds (P, Q, S) using HNO₃/H₂SO₄ (nitrating mixture). Nitration is an electrophilic aromatic substitution reaction where a nitro group (-NO₂) is introduced. The position of substitution depends on the existing substituents on the benzene ring, which can be activating (ortho/para directing) or deactivating (meta directing).

Step 1: Analyze each compound's substituent effects

Compound P has a -NHCOCH₃ (acetanilide) group. The -NHCOCH₃ is an ortho/para director because the nitrogen lone pair is conjugated into the ring (though less activating than -NH₂ due to carbonyl withdrawal). Nitration occurs primarily at the para position (ortho is sterically hindered).

Compound Q has a -NO₂ group. Nitro group is strongly deactivating and meta-directing. Nitration will occur meta to the nitro group.

Compound S has a -Cl group. Chlorine is deactivating due to electronegativity but ortho/para directing due to lone pair resonance. Nitration occurs at ortho and para positions, with para often favored due to sterics.

Step 2: Predict the major product for each

For P: Major product is para-substituted relative to -NHCOCH₃.

For Q: Major product is meta-substituted relative to -NO₂.

For S: Major product is para-substituted relative to -Cl (ortho is possible but para is less sterically hindered).

Step 3: Match with options

Review the given options to identify which one shows:

• P with nitro para to -NHCOCH₃
• Q with nitro meta to -NO₂
• S with nitro para to -Cl

Final Answer: The correct option is the one where P has para-nitro, Q has meta-nitro, and S has para-nitro substitution.

Related Topics & Formulae

Electrophilic Aromatic Substitution: Reactions like nitration, halogenation, sulfonation follow this mechanism. The directing effects depend on substituents:

• Activating groups (e.g., -OH, -NH₂, -OR): Ortho/para directors
• Deactivating groups (e.g., -NO₂, -CN, -COOH): Meta directors
• Halogens (-Cl, -Br): Deactivating but ortho/para directors

Key Theory: Substituents affect electron density via resonance and inductive effects. Ortho/para directors donate electrons (or have lone pairs), while meta withdraw electrons.