Aldehydes And Ketones(12th Grade > Chemistry ) Questions and Answers
Question 1. Which of the following has the most acidic hydrogen?
3-Hexanone
2,4-Hexanedione
2,5-Hexanedione
2,3-Hexanedione
Explanation:-
Answer: Option B. -> 2,4-Hexanedione : B (a) (b) (c) (d) Here, (b) has most acidic hydrogen. Since in (b), C-3 is directly attached with two EWG (C=O) groups which make hydrogens at C-3 most acidic.
Question 2. This polymer is obtained when acetone is saturated with hydrogen chloride gas. Polymer is:
phorone
formose
diacetonyl alcohol
mesityl oxide
Explanation:-
Answer: Option A. -> phorone : A The product formed by the shown condensation reaction is called Phorone.
Question 3. Oppenauer oxidation is the reverse process of:
Wolff-Kishner’s reduction
Rosenmund’s reduction
Clemmensen’s reduction
Meerwein-Ponndorf Verley reduction
Explanation:-
Answer: Option D. -> Meerwein-Ponndorf Verley reduction : D OPPENAUER OXIDATION & MEERWIN-PONDORFF-VERLEY REDUCTION
Question 4. HCHO and HCOOH are distinguished by treating with:
Tollen’s reagent
NaHCO3
Fehling’s solution
Benedict solution
Explanation:-
Answer: Option B. -> NaHCO3 : B HCOOH reacts with NaHCO3 producing effervescence of CO2 but not HCHO.
Question 5. A ketone reacted with C2H5MgBr reagent followed by hydrolysis gave a product which on dehydration gives an alkene. The alkene on ozonolysis gave diethyl ketone and acetaldehyde. The ketone is:
dimethyl ketone
ethyl methyl ketone
diethyl ketone
ethyl propyl ketone
Explanation:-
Answer: Option C. -> diethyl ketone : C
Question 6.CH3COOEtCH3MgBr−−−−−−→ExcessP
Explanation:-
Answer: Option C. -> diethyl ketone : A
Question 7. One mole of an organic compound requires 0.5 mole of oxygen to produce an acid. The compound may be:
alcohol
ether
ketone
aldehyde
Explanation:-
Answer: Option D. -> aldehyde : D CH3CHO+(O)→CH3COOH
Question 8. The difference between aldol condensation and Cannizzaro’s reaction is that:
the former takes place in the presence of α-H-atom
the former takes place in the absence of α−H−atom
the former takes place in the presence of β−H−atom
none of the above
Explanation:-
Answer: Option A. -> the former takes place in the presence of α-H-atom : A Aldol condensation occurs in presence of α-hydrogens but cannizzaro’s reaction occurs in the absence of α−hydrogens.
Question 9. The decreasing order of solubility of methanal (A), propanaldehyde (B), benzaldehyde (C) and acetophenone (D):
A>B>C>D
D>C>B>A
D>A>B>C
B>A>C>D
Explanation:-
Answer: Option A. -> A>B>C>D : A Solubility decreases due to increase in molecular weight as a result of increase in hydrophobic nature of the alkyl group.