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All questions of Aldehydes, Ketones and Carboxylic Acids for ACT Exam

The IUPAC name of CH3CHO is:
  • a)
    Acetaldehyde
  • b)
    Ethanal
  • c)
    Formaldehyde
  • d)
    Methanal
Correct answer is option 'A'. Can you explain this answer?

Riya Banerjee answered
  • The functional group is an aldehyde; −CHO and the given compound has two carbon atoms.
  • Thus, the IUPAC name of the compound is ethanal.

Reaction
Primary amine + CHCl3 + KOH → product, here product will be -         [AIEEE-2002]
  • a)
    Cyanide
  • b)
    Isocyanide
  • c)
    Amine
  • d)
    Alcohol
Correct answer is option 'B'. Can you explain this answer?

Krishna Iyer answered
The correct answer is Option B.
When primary amine reacts with CHCl3 in alcoholic KOH, the product is isocyanide which is foul smelling.
R−NH2+CHCl3+3KOH -ΔR−NC+3KCl+3H2O
This reaction is known as carbylamine test / Isocyande test. This test is not given by secondary or tertiary amines.

 Which of the following statements are correct in case of the carbonyl bond between carbon and oxygen?
  • a)
    Carbon is the nucleophilic centre and Oxygen is the electrophilic centre.
  • b)
    Oxygen is the nucleophilic centre and Carbon is the electrophilic centre.
  • c)
    Carbon and Oxygen double bond is polarised.
  • d)
    Both ‘b’ and ‘c’ are correct
Correct answer is option 'C'. Can you explain this answer?

Nandini Patel answered
The double bonds in alkenes and double bonds in carbonyl groups are VERY different in terms of reactivity. The C=C is less reactive due to C=O electronegativity attributed to the oxygen and its two lone pairs of electrons.  One pair of the oxygen lone pairs are located in 2s while the other pair are in 2p orbital where its axis is directed perpendicular to the direction of the pi orbitals.  The Carbonyl groups properties are directly tied to its electronic structure as well as geometric positioning.  For example, the electronegativity of oxygen also polarizes the pi bond allowing the single bonded substituent connected to become electron withdrawing.

What is the IUPAC name of Acrolein?
  • a)
    pent-2-enal
  • b)
    but-1-enal
  • c)
    prop-2-enal
  • d)
    but-2-enal
Correct answer is option 'C'. Can you explain this answer?

Nandini Iyer answered
IUPAC name of acrolein is prop-2-enal, a name derived from that of acrylic acid, the parent carboxylic acid.

Propanone and prop-2-en-1-ol are examples of which type of isomerism?
  • a)
    Functional isomers
  • b)
    Chain isomers
  • c)
    Tautomers
  • d)
    Position isomers
Correct answer is option 'A'. Can you explain this answer?

Abhijeet Menon answered
Functional isomers:

Functional isomers are compounds that have the same molecular formula but differ in their functional groups. In other words, functional isomers have different chemical properties because they have different functional groups.

Propanone (CH3COCH3) and prop-2-en-1-ol (CH3CH=CHCH2OH) are examples of functional isomers because they have different functional groups. Propanone has a ketone functional group whereas prop-2-en-1-ol has an alcohol functional group.

Ketones and alcohols have different chemical properties and reactivities because of the differences in their functional groups. Therefore, propanone and prop-2-en-1-ol are functional isomers.

 Which of the following statement about C=O and C=C is correct?
  • a)
    Both consist of a sigma and pi bond
  • b)
    C=O is polar but C=C is non-polar
  • c)
    Both a and b are correct
  • d)
    Both C=O and C=C undergo nucleophilic addition reactions
Correct answer is option 'C'. Can you explain this answer?

Vishal Giri answered
Yes I think Option C is correct. Because so............ if it form more than one bond with same another atom ( here O & C) except one all another will pi bonds. here two bonds that means definitely one is sigma and another is pi bond.There is difference between electronegetivity of C and O ( O is more electronegetive than C) hence C=O is polar while there is same electronegetivity of both C in C=C hence it is nonpolar .

What is the common name of 2-methyl-propanal?
  • a)
    formaldehyde
  • b)
    Isobutyraldehyde
  • c)
    carbaldehyde
  • d)
    acetaldehyde
Correct answer is 'B'. Can you explain this answer?

Nikita Singh answered
  • Isobutyraldehyde is the chemical compound with the formula (CH₃)₂CHCHO.
  • It is an aldehyde, isomeric with n-butyraldehyde.
  • Isobutyraldehyde is manufactured, often as a side-product, by the hydroformylation of propene. Its odour is described as that of wet cereal or straw.

Identify the pair of enantiomers amongst the given pairs:
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'B'. Can you explain this answer?

Nandini Iyer answered
The correct answer is Option B.
The 1st option has R configuration and 2nd has S configuration hence they are non super imposable mirror images of each other and are enantiomers.

The general formula CnH2nO2 could be for open chain :         [AIEEE-2003]
  • a)
    Diols
  • b)
    Dialdehydes
  • c)
    Diketones
  • d)
    Carboxylic acid
Correct answer is option 'D'. Can you explain this answer?

Hansa Sharma answered
The correct answer is option D
The general formula Cn​H2n​O2​ could be for open chain carboxylic acids. Thus, butanoic acid CH3​−CH2​−CH2​−COOH has formula C4​H8​O2​. And, decanoic acid CH3​−(CH​2)8​−COOH has formula C10​H20​O2.​.

Which one of the following methods is neither meant for the synthesis nor for separation of amines ?
[AIEEE-2005]
  • a)
    Hofmann method
  • b)
    Hinsberg method
  • c)
    Curtius reaction
  • d)
    Wurtz reaction
Correct answer is option 'D'. Can you explain this answer?

Nikita Singh answered
The correct answer is Option D.
Wurtz reaction is used to produce alkanes from alkyl halides.
2RX+2Na (in ether)→R−R+2NaX
Example :
2CH3Cl+2Na (in ether)→C2H6+2NaCl
So, the Wurtz reaction has nothing to do with amines.

Rate of the reaction :
is fastest when Z is :              [AIEEE-2004]
  • a)
    OCOCH3
  • b)
    NH2
  • c)
    OC2H5
  • d)
    Cl
Correct answer is option 'D'. Can you explain this answer?

Preeti Iyer answered
The correct answer is Option D.
Cl is the best leaving group being the weakest nucleophile out of NH2− , Cl− , OC2H5 and CH3COO
So, when Z is Cl , the ion leaves faster thus making the reaction the fastest when Z is Cl .

In the chemical reaction, CH3CH2NH2 + CHCl3 + 3KOH → (A) + (B) + 3H2O, the compounds (A) and (B)
are respectively -     [AIEEE-2007]
  • a)
    C2H5CN and 3KCl
  • b)
    CH3CH2CONH2 and 3KCl
  • c)
    C2H5NC and K2CO3
  • d)
    C2H5NC and 3KCl
Correct answer is option 'D'. Can you explain this answer?

Lavanya Menon answered
The correct answer is option D
In the chemical reaction,
CH3​CH2​NH2​+CHCl3​+3KOH→(A)+(B)+3H2​O
The compounds(A) and (B) are C2​H5​NC and 3KCl respectively. The given reaction is carbylamine test/Isocyanide test in which aliphatic or aromatic primary amines on heating with chloroform and alcoholic potassium hydroxide give foul smelling alkyl isocyanides or carbylamines. Secondary or tertiary amines do not give this test.

When CH2 = CHCOOH is reduced with LiAlH4, the compound obtained is:      [AIEEE-2003]
a) CH3CH2CH2OH
b) CH3CH2CHO
c) CH2=CH-CH2OH
d) CH3CH2COOH
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
The correct answer is option C
LiAlH4  can reduce the carboxylic acid group without affecting the double bond because alkene is an electron-rich species.

In which of the following reactions, ketone is formed as the major organic product?
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A,C'. Can you explain this answer?

Om Desai answered
If acid derivatives like nitrile, acid chlorid e or ester is taken in excess in Grignard synthesis, second addition of Grignard’s reagent on carbonyl product does not succeed and carbonyls are obtained as major products.
In option (b), carboxylic acids and in option (d), an aldehyde is formed.

A strong base can abstract an α – hydrogen from
  • a)
    Alkane.
  • b)
    Amine
  • c)
    Ketone
  • d)
    Alkene
Correct answer is option 'C'. Can you explain this answer?

Vijay Bansal answered
After deprotonation the negative charge will be in conjugation with the pi orbital of carbonyl..so base will prefer to abstract alpha hydrogen from ketone.

IUPAC name of compound
  • a)
    3-Bromo7-chloro-7ethyl-5-(1,1-dimethyethyl)-5-(2-methylpropyl)-3-methylnonane
  • b)
    3-Bromo7-chloro-5-(1,1-dimethyethyl)-7-ethyl-3methyl-5-(2-methylpropyl)nonane
  • c)
    3-Bromo7-chloro-7ethyl-3-,methyl-5-(1,1-dimethyethyl)-5-(2-methylpropyl)nonane
  • d)
    3-Bromo-5-(1,1-dimethyethyl)-5-(2-methylpropyl)-7-chloro-7ethyl-5--3-methylnonane
Correct answer is option 'B'. Can you explain this answer?

The correct answer is option B
First of all, we should number the carbon atoms from right to left for the above molecule. According to IUPAC rule, we have to name the functional groups alphabetically. Hence, bromine which is attached to 3rd carbon is named as 3-bromo, chlorine which is attached to 7th carbon is named as 7-chloro and ethyl group which is also attached to 7th carbon is named as 7-ethyl. 5-(1,1-dimethyethyl) indicates that, 2 methyl groups are attached to the 1st carbon of ethyl group which is attached to the 5th carbon of the given molecule. 5-(2-methylpropyl) indicates that, a methyl group is attached to the 2nd carbon of propyl group which is attached to the 5th carbon of the given molecule. Finally, since the molecule has nine atoms and it is an alkane, the word nonane is added to the IUPAC name.
 

The compound formed as a result of oxidation of ethyl benzene by KMnO4 is –        [AIEEE-2007]
  • a)
    benzophenone
  • b)
    acetophenone
  • c)
    benzoic acid
  • d)
    benzyl alcohol
Correct answer is option 'C'. Can you explain this answer?

Rishu Verma answered
Any benzene derivative ( benzene alkyl ) which have at least one alpha hydrogen gives benzoic acid on oxidation with kmno4 ........what ever the lenght or no of carbon atom on benzene if it has alpha hydrogen it will oxidise to carboxylic grp

A liquid was mixed with ethanol and a drop of concentrated H2SO4 was added. A compound with a fruity
smell was formed. The liquid was :         [AIEEE-2009]
  • a)
    CH3OH
  • b)
    HCHO
  • c)
    CH3COCH3
  • d)
    CH3COOH
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
The correct answer is Option D.
The fruity smell is evolved due to the formation of ester when ethanol and acid are treated in the presence of concentrated H2SO4.
The reaction is 
CH3COOH + CH3CH2OH → CH3COOC2H5

Which one of the following is reduced with zinc and hydrochloric acid to give the corresponding
hydrocarbon :        [AIEEE-2004]
  • a)
    Butan-2-one
  • b)
    Acetic acid
  • c)
    Acetamide
  • d)
    Ethyl acetate
Correct answer is option 'A'. Can you explain this answer?

Priya Patel answered
Butan-2-one will get reduced into butane when treated with zinc and hydrochloric acid following Clemmensen reduction reaction whereas zn/HCl do not reduce ester,acid and amide.

Arrange the following compounds in decreasing order of their acid strength: i) trichloroacetic acid ii) trifluoroacetic acid iii) acetic acid and iv) formic acid
  • a)
    trifluoroacetic acid, trichloroacetic acid, formic acid and acetic acid
  • b)
    formic acid., trifluoroacetic acid, trichloroacetic acid, and acetic acid
  • c)
    trichloroacetic acid, trifluoroacetic acid, acetic acid and formic acid.
  • d)
    trifluoroacetic acid, formic acid acetic acid and Propan – 1 – ol, 4 – methylphenol
Correct answer is option 'A'. Can you explain this answer?

Tanuja Kapoor answered
Acidic strength of carboxylic acid -
–  More acidic than phenols or alcohols.
–  Acidity increase with the presence of a group with  -I effect in the alkyl group.Whereas it decreases with the presence of  +I group.
–  Acidity increases with increase in the number of halogen atoms on  - position.
–  It decreases with increasing distance of halogen from   
–  It increases with increase in the electronegativity of halogen.
- CF3COOH > CCl3COOH > HCOOH > CH3 COOH

Consider the acidity of the carboxylic acids :
(1) PhCOOH
(2) 0-NO2C6H4COOH
(3) p-NO2C6H4COOH
(4) m-NO2C6H4COOH
Which of the following order is correct ?     [AIEEE-2004]
  • a)
    2 > 3 > 4 > 1
  • b)
    2 > 4 > 3 > 1
  • c)
    2 > 4 > 1 > 3
  • d)
    1 > 2 > 3 > 4
Correct answer is option 'A'. Can you explain this answer?

Vivek answered
Ortho derivative of Benzoic acid is most acidic regardless of the nature of the group at that position. Para derivative is on the 2nd position due to electron withdrawing effect due to -R and -I effect. Meta derivative comes 3rd due to -I effect only (as meta position is not involved in resonance). At last comes Benzoic acid which is least acidic due to absence of any electron withdrawing group.

How manyh assymmetric carbon atoms are present in
(i) 2-Dimethyl cyclohexane
(ii) 3-Methyl cyclopentene
(iii) 3-Methylcyclohexene
  • a)
    2,1,1
  • b)
    1,1,1
  • c)
    2,0.2
  • d)
    2,0,1
Correct answer is option 'A'. Can you explain this answer?

Aarya Khanna answered
Asymmetric carbon atoms are those carbon atoms which are attached to four different groups or atoms. These carbon atoms are also known as chiral centers.

(i) 2-Dimethyl cyclohexane:
- Cyclohexane has no asymmetric carbon atoms.
- When two methyl groups are attached to cyclohexane, it becomes 2,3-dimethyl cyclohexane.
- The carbon at position 2 is attached to two methyl groups and two hydrogen atoms. Therefore, it is not an asymmetric carbon atom.
- The carbon at position 3 is attached to one methyl group, one hydrogen atom, one methyl group, and one cyclohexane ring. Therefore, it is an asymmetric carbon atom.
- Hence, there is one asymmetric carbon atom in 2-dimethyl cyclohexane.

(ii) 3-Methyl cyclopentene:
- Cyclopentene has one asymmetric carbon atom.
- When a methyl group is attached to cyclopentene at position 3, it becomes 3-methyl cyclopentene.
- The carbon at position 3 is attached to one methyl group, one hydrogen atom, one double bond with carbon, and one cyclopentene ring. Therefore, it is an asymmetric carbon atom.
- Hence, there is one asymmetric carbon atom in 3-methyl cyclopentene.

(iii) 3-Methylcyclohexene:
- Cyclohexene has one asymmetric carbon atom.
- When a methyl group is attached to cyclohexene at position 3, it becomes 3-methylcyclohexene.
- The carbon at position 3 is attached to one methyl group, one hydrogen atom, one double bond with carbon, and one cyclohexene ring. Therefore, it is an asymmetric carbon atom.
- Hence, there is one asymmetric carbon atom in 3-methylcyclohexene.

Therefore, the correct answer is option 'A' (2,1,1) as there are 2 asymmetric carbon atoms in total, with 1 in 2-dimethyl cyclohexane, 1 in 3-methyl cyclopentene, and 1 in 3-methylcyclohexene.

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