A) if both assertion and reason are true and reason is the correct explanation of assertion.

Benzaldehyde reduces Tollen's reagent, but does not reduce Fehling's solution. Because Ag⁺ is more easily reduced to Ag than Cu²⁺ to Cu⁺

The order of reactivity of aliphatic carbonyl compounds towards the nudeophilic addition reaction is, HCHO > CH₃CHO > CH₃COCH₃

When calcium acetate is dry distilled, acetone is formed.

The angle between the incident and deviated light ray is called angle of deviation of the light ray.

An carbonyl compound having molecular formula C₅H₁₀O giving positive iodoform test. It does not reduce Fehling solution.So it is 2- pentanone.

∴ (A) is 2-pentanone.

(i) An organic compound (A) with formula C₇H₆O form bisulphite means it must be benzaldehyde C₆H₅CHO.
(ii) Benzaldehyde on treatment with KCN form benzoin.
\(\underset { (A) }{ { C }_{ 6 }{ H }_{ 5 }CHO+{ C }_{ 6 }{ H }_{ 5 }CHO } \overset { KCN }{ \longrightarrow } \underset { (B) }{ { C }_{ 6 }{ H }_{ 5 }-\underset { \overset { | }{ HO } }{ CH } -\underset { \overset { || }{ O } }{ C } -{ C }_{ 6 }{ H }_{ 5 } } \) 
(iii) Benzaldehyde on treatment with sodium acetate and acetic anhydride form an acid, cinnamic acid it is (C).
\(\underset { (A) }{ { C }_{ 6 }{ H }_{ 5 }CHO } +\left( { CH }_{ 3 }{ CO } \right) O\overset { { CH }_{ 3 }COONa }{ \longrightarrow } \underset { (C) }{ { C }_{ 6 }{ H }_{ 5 }CH } =CH-COOH+CH_{ 3 }COOH\)

Acidic nature of acids:
(i) Acid molecule ionises to produce H⁺ ions in solution.

(ii) The carboxylate anion is stabilised by resonance.

Hence the cleavage of -COOH bond to release H⁺ is favoured, thereby making it to behave as acids.
(iii) Any factor that weakens the -COOH bond will facilitate the cleavage to release H⁺ more easily. The degree of ionisation is increased and acid becomes relatively a stronger acid.
(iv) When the following acids are compared
Their strength varies as the above order.
(v) Methyl group is a + I group (electron pair repelling group). Acid strength decreases: with increasing number of electron repelling substituent attached to the α- carbon atom.

The +1 effect is felt in increasing the strength of the -OH bond and the cleavage to form H+ becomes difficult. Hence they are weaker acid than formic acid (HCOOH) which does not have + I methyl group.
(vi) Acid strength increases with increase in electronegativity of substituents

This effect weakness the -O- H bond there by facilitating the removal of H⁺ from -OH group. This acid becomes stronger than formic acid.

Primary alcohols and aldehydes can easily be oxidised to the corresponding carboxylic acids with oxidising agents such as potassium permanganate (in acidic or alkaline medium), potassium dichromate (in acidic medium)
Example:
\(\underset{Ethyl \ alcohol}{ { CH }_{ 3 }{ CH }_{ 2 }OH}\overset { { H }^{ + }/{ K }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 } }{ \underset { (O) }{ \longrightarrow } } \underset{Acetaldehyde}{{ CH }_{ 3 }CHO}\underset { (O) }{ \longrightarrow } \underset{Acetic \ acid}{{ CH }_{ 3 }COOH}\)

(i) Cannizzaro reaction is a redox reaction which takes place only in aldehydes which do not have α- hydrogen atom.
(ii) Formaldehyde (HCHO) and benzaldehyde (C₆H₅CHO) do not have a-hydrogen atom and so they undergo Cannizzaro reaction.
(iii) But acetaldehyde CH₃CHO contains 3 α-H atoms and it does not undergo Cannizzaro reaction.

Ozone forms addition product with olefin called I ozonide, which on reductive cleavage gives aldehyde.

2- Pentanone.