This question tests your understanding of electrophilic aromatic substitution, specifically nitration, and how substituents on the benzene ring direct the incoming nitro group (NO₂⁺) to the ortho, meta, or para positions.

The key concept is that substituents are classified as ortho-para directing activators, ortho-para directing deactivators, or meta directing deactivators. A "significant amount of meta product" will be formed primarily when the substituent on the ring is a meta-directing deactivator.

These groups are electron-withdrawing and destabilize the carbocation intermediate formed during the reaction. The meta-position is less electron-deficient compared to the ortho and para positions relative to the substituent, making it the favored site for attack. Common meta-directing groups include:

• Nitro ($-N{O}_2$)
• Cyano ($-C\equiv N$)
• Carbonyl groups like Aldehyde ($-CHO$), Ketone ($-COR$)
• Carboxylic Acid ($-COOH$)
• Sulfonic acid ($-S{O}_{3}H$)
• Ammonium ($-N_3{}^{+}$)

To solve this, you must identify which compound among the options has a substituent that falls into this meta-directing deactivator category.

Step-by-Step Analysis of the Options:

Since the exact structures from the images are not provided in text, I will describe the common compounds these images typically represent and their directing effects.

Option 1: This image often represents Phenol (C₆H₅OH).
The -OH group is a strong ortho-para directing activator. It will produce primarily ortho and para nitration products. A significant meta product will NOT be formed.

Option 2: This image often represents Aniline (C₆H₅NH₂) or a similar compound.
The -NH₂ group is a very strong ortho-para directing activator. It will also not produce a significant meta product.

Option 3: This image often represents Toluene (C₆H₅CH₃).
The -CH₃ group is an ortho-para directing activator (though weaker than -OH or -NH₂). It directs substitution to the ortho and para positions.

Option 4: This image often represents Nitrobenzene (C₆H₅NO₂) or Benzoic acid (C₆H₅COOH).
Both the -NO₂ and -COOH groups are classic meta-directing deactivators. Nitration of these compounds occurs primarily at the meta position, yielding a significant amount of meta product.

Final Answer:

Therefore, the compound in Option 4 (likely Nitrobenzene or Benzoic acid) is the one that will form a significant amount of meta product during mono-nitration.

Related Topics & Formulae:

Electrophilic Aromatic Substitution (EAS): The general mechanism for reactions like nitration, halogenation, sulfonation, and Friedel-Crafts alkylation/acylation. The rate and regioselectivity are governed by the nature of the substituent already present on the ring.

Directing Effects:

• Activating, Ortho-Para Directors: Electron-donating groups (EDG) like -OH, -NH₂, -OR, -R. They stabilize the carbocation intermediate.
• Deactivating, Meta Directors: Electron-withdrawing groups (EWG) like -NO₂, -CN, -COR, -COOH, -SO₃H. They destabilize the carbocation intermediate.
• Deactivating, Ortho-Para Directors: Halogens (-Cl, -Br, -I). They are electron-withdrawing inductively but electron-donating by resonance, resulting in ortho/para direction but overall deactivation.

Resonance Theory: The directing effect is best explained by drawing the resonance structures of the carbocation (sigma complex) intermediate formed when the electrophile attacks the ortho, meta, and para positions. A meta-directing group ensures that no resonance structure places the positive charge on the carbon atom directly attached to it, which is highly destabilized.