Structural and Physical Properties of Carbonyls

Q. The decreasing order of solubility of methanal (A), propanaldehyde (B), benzaldehyde (C) and acetophenone (D):

1. A > B > C > D
2. D > C > B > A
3. D > A > B > C
4. B > A > C > D

Q. Arrange the following in order of increasing reactivity towards Grignard reagent -

1. II > I > IV > III
2. III > II > I > IV
3. IV > III > II > I
4. I > II > III > IV

Q. An organic compound X with molecular formula $C_5{H}_{10}O$ gives test with phenyl hydrazine but gives a negative response to iodoform test and Tollen’s test. It produces n-pentane on reduction. The compound could be

1. pentan-2-one
2. pentanal
3. pentan-3-one
4. amyl alcohol

Q. Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their

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1. More extensive association of carboxylic acid via van der Waals force of attraction
2. Formation of intermolecular H-bonding
3. Formation of intramolecular H-bonding
4. Formation of carboxylate ion

Q. The boiling points of aldehydes and ketones lie in between alkanes and alcohols of comparable masses because:

1. aldehydes and ketones are non-polar
2. alkanes are non-polar and aldehydes and ketones contain polar group and lower alcohols have H-bonding
3. alkanes are held together by weak van der Waals’ forces (being non-polar), aldehydes and ketones contain polar and held together by strong dipole-dipole attraction and lower alcohols have H-bonding, which is stronger than dipole-dipole attraction
4. alkanes are polar

Q.

Identify the correct order of boiling points of the following compounds.

1. $C{H}_3(C{H}_2{)}_{2}C{H}_{2}OH$
2. $C{H}_3(C{H}_2{)}_{2}CHO$
3. $C{H}_3(C{H}_2{)}_{2}COOH$

1. 1 > 2 > 3
2. 3 > 1 > 2
3. 1 > 3 > 2
4. 3 > 2 > 1

Q. HCHO and HCOOH are distinguished by treating with:

1. NaHCO₃
2. Fehling’s solution
3. Benedict solution
4. Tollen’s reagent

Q.

Which of the following is most stable, and which one is least ?
$HCHO$ $C{H}_{3}CHO$
I II

$C{H}_{3}COC{H}_3$ $C{l}_{3}CCHO$
III IV

1. All the four all equally stable

2. IV is most stable and I is least

3. III is most stable and I is least

4. III is most stable and IV is least

Q.

The correct stability order of the following three quinones is ?

1. I = III > II

2. III > I > II

3. I = II > III

4. I > III > II

Q.

Observe the following structures and pick up the correct statement ?

1. Carbonyl carbon of I is more electrophilic than that of II

2. Carbonyl carbon of I is less electrophilic than that of II

3. Carbonyl carbon of both structures have equal electrophilic character
   

4. It depends upon the complete structure of the compound