Directions: Each question contains Statement- 1 and Statement- 2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct. (a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1 (b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1 (c) Statement- 1 is True, Statement- 2 is False (d) Statement- 1 is False, Statement- 2 is True Statement 1 During nucleophilic addition to carbonyl compounds, strong acid conditions are not favourable. and Statement 2 Strong acids decrease the reactivity of carbonyl compounds.

Carbonyl compounds, which include aldehydes and ketones, possess a unique structural feature: a carbon atom double-bonded to an oxygen atom. This arrangement results in a polar bond due to oxygen's higher electronegativity compared to carbon, leaving the carbon atom electron-deficient and creating a partial positive charge. Consequently, carbonyl carbons become attractive targets for nucleophiles—species that are rich in electrons.

The reactivity of these compounds is intrinsically linked to this electrophilic character of the carbonyl carbon. Factors that increase the positive charge on the carbonyl carbon enhance its reactivity towards nucleophilic attack. Conversely, any factor that diminishes this partial positive charge or hinders the approach of a nucleophile can decrease the carbonyl compound's reactivity.

For instance, electron-withdrawing groups attached to the carbonyl compound can intensify the carbon’s electrophilic nature, thereby increasing reactivity. In contrast, steric hindrance or the presence of electron-donating groups can decrease the reactivity by reducing the accessibility to the carbonyl carbon or by diminishing its electrophilic character.

In the realm of organic chemistry, strong acids are often utilized to catalyze reactions or modify the reactivity of organic compounds. Strong acids, like sulfuric acid or hydrochloric acid, can readily donate protons (H+) to their surroundings, creating highly acidic conditions.

The impact of these conditions on organic reactions is significant. A key effect is the protonation of nucleophilic species that are present in the reaction mixture. Under acidic conditions, nucleophiles such as water, alcohols, or amines can become protonated, transforming them into their conjugate acids, which are far less nucleophilic because they carry a positive charge.

Moreover, the protonation of the carbonyl oxygen can occur in strong acid conditions, forming a resonance-stabilized carbocation, which should, theoretically, increase the electrophilicity of the carbonyl carbon. However, this protonated form can be less reactive in nucleophilic addition reactions due to the formation of additional resonance structures that distribute the positive charge, thereby reducing the polarization of the carbonyl group and its reactivity.

Nucleophilic addition is a fundamental reaction mechanism in organic chemistry, particularly relevant to carbonyl compounds. In this process, a nucleophile, which has a lone pair of electrons, attacks an electrophilic carbon atom, leading to the formation of a new covalent bond.

The mechanism typically unfolds in two distinct steps:

• The nucleophile approaches the carbonyl compound and forms a bond with the electrophilic carbonyl carbon, pushing the double bond's electrons onto the oxygen atom. This results in a tetrahedral intermediate, which can stabilize through resonance if possible.
• The intermediate resolves into a stable compound, which may involve the loss of a leaving group or the addition of a proton (in the case of aldehydes and ketones, the leaving group is usually a proton from a nearby solvent molecule).

Step-by-step, the reaction pathway can vary depending on the specific nucleophile and carbonyl compound involved, as well as the reaction conditions, such as the presence of acids or bases. The solvent also plays a crucial role as it may facilitate or inhibit the reaction depending on its properties, like polarity and ability to form hydrogen bonds.