Hydrocarbons Test

Result

Hydrocarbons Test - 31

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Weekly Quiz Competition

Question 1
1 / -0

Match the reagent from Column I which on reaction with CH₃—CH = CH₂ gives some product given in Column II as per the codes given below:

A
A. (i) → (d) (ii) → (a) (iii) → (e) (iv) → (c) (v) → (b)

B
B. (i) → (a) (ii) → (a) (iii) → (e) (iv) → (c) (v) → (b)

C
C. (i) → (b) (ii) → (a) (iii) → (e) (iv) → (c) (v) → (b)

D
D. (i) → (c) (ii) → (a) (iii) → (e) (iv) → (c) (v) → (b)

Solution

(i) O₃/Zn + H₂O - Two carbonyl compounds are obtained on ozonolysis of alkene
(ii) KMnO₄/H⁺ - Propene gives CH₃COOH and CO₂ on reacting with KMnO₄in an acidic medium.
(iii) KMnO₄/OH^– - Alkaline KMnO₄ is decolourised by propene.
(iv) H₂O/H⁺ - Propanol-2 is obtained when H₂O is added to propene
(v) B₂H₆/NaOH and H₂O₂ - Propanol-1 is obtained as a product.
Question 2
1 / -0

Match the following reactants in Column I with the corresponding reaction products in Column II.

A
A. (i) → (d) (ii) → (c) (iii) → (b) (iv) → (a)

B
B. (i) → (a) (ii) → (c) (iii) → (b) (iv) → (a)

C
C. (i) → (b) (ii) → (c) (iii) → (b) (iv) → (a)

D
D. (i) → (c) (ii) → (c) (iii) → (b) (iv) → (a)

Solution
Question 3
1 / -0

Match the reactions given in Column I with the reaction types in Column II.

A
A. (i) → (d) (ii) → (a) (iii) → (b) (iv) → (c)

B
B. (i) → (a) (ii) → (a) (iii) → (b) (iv) → (c)

C
C. (i) → (b) (ii) → (a) (iii) → (b) (iv) → (c)

D
D. (i) → (c) (ii) → (a) (iii) → (b) (iv) → (c)
Solution
In reaction (i) H₂O molecule added to alkene and formation of ethanol, which is a example of hydration reaction. In reaction
(ii) one H₂ molecule add with ethylene formation of ethane. The reaction where H₂ reacts with a compound in presence of Pd catalyst is called hydrogenation reaction. In reaction
(iii) Cl₂ molecule add to ethylene formation of dichloro compound. This type of halogen addition reactions are termed as halogenation reaction.
In reaction (iv) 3 ethyne molecule act as a monomer unit, which combine and forming cyclic benzene molecule. So, this type of reaction where joining of molecule and forming products is called polymerisation reaction.
Question 4
1 / -0

Match the hydrocarbons in Column I with the boiling points given in Column II.

A
A. (i) → (b) (ii) → (c) (iii) → (a)

B
B. (i) → (a) (ii) → (c) (iii) → (a)

C
C. (i) → (c) (ii) → (c) (iii) → (a)

D
D. (i) → (d) (ii) → (c) (iii) → (a)

Solution

(i) n–Pentane: In n-pentane there is no branching and surface area. Hence , more Vander Waal's forces. Therefore , boiling point is high.
(ii) iso-Pentane: Molar mass is same but one branch is there which reduces its surface area. Hence the boiling point is less.
(iii) neo-Pentane: In this compound two sides chain are there having the same molar mass. Therefore , its boiling point is lowest amongst all three compounds.
Question 5
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : The compound cyclooctane has the following structural formula :
It is cyclic and has a conjugated 8π-electron system but it is not an aromatic compound.
Reason (R) : (4n + 2) π electrons rule does not hold good and the ring is not planar.

A
Both A and R are correct and R is the correct explanation of A.

B
Both A and R are correct but R is not the correct explanation of A.

C
Both A and R are not correct.

D
A is not correct but R is correct.
Solution
Aromaticity is shown by compounds possessing following characteristics:
Planarity
Complete delocalization of the π electrons in the ring.
Presence of (4n+2)π electrons in the ring where n is an integer (4 = 0, 1, 2..)
This is often referred to as Huckel’s Rule.
According to Huckel's Rule, the given compound is Antiaromatic.
Question 6
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : Nitration of benzene with nitric acid requires the use of concentrated sulphuric acid.
Reason (R) : The mixture of concentrated sulphuric acid and concentrated nitric acid produces the electrophile, NO₂⁺.

A
A. Both A and R are correct and R is the correct explanation of A.

B
B. Both A and R are correct but R is not the correct explanation of A.

C
C. Both A and R are not correct.

D
D. A is not correct but R is correct.

Solution

In nitration , benzene is treating with nitrating mixture , i.e., conc. HNO₃ and H₂SO₄ and H₂SO₄ helps in furnishing NO₂⁺ (Electrophile).
Question 7
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : Among isomeric pentanes, 2, 2-dimethylpentane has the highest boiling point.
Reason (R) : Branching does not affect the boiling point.

A
A. Both A and R are correct and R is the correct explanation of A.

B
B. Both A and R are correct but R is not the correct explanation of A.

C
C. Both A and R are not correct.

D
D. A is not correct but R is correct.

Solution

Assertion (A): Among isomeric pentanes, 2, 2-dimethylpentane has lowest boiling point. Reason (R): Branching affects boiling point. More are the branches, lower the boiling point it possess.
Question 8
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : Toluene on Friedel-Crafts methylation gives o– and p–xylene.
Reason (R) : CH₃-group bonded to the benzene ring increases electron density at o– and p– position.

A
A. Both A and R are correct and R is the correct explanation of A.

B
B. Both A and R are correct but R is not the correct explanation of A.

C
C. Both A and R are not correct.

D
D. A is not correct but R is correct.

Solution

Toluene has −CH₃ group attached to benzene ring. CH₃ group is electron withdrawing group which deactivates benzene ring due to hyperconjugation effect and increases electron density on ortho and para positions for the attack of electrophiles.
Question 9
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion: Saturated hydrocarbons are chemically less reactive.
Reason : All isomeric paraffins have same parent name.

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

B
B. If both assertion and reason are true but reason is not the correct explanation of assertion.

C
C. If assertion is true but reason is false.

D
D. If both assertion and reason are false.

Solution

Less reactivity of saturated hydrocarbons is due to the presence of single bonds between carbon atoms. Paraffins (alkanes) may have straight chain or branched chain isomers which have different parent names.
Question 10
1 / -0

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion : H₂O₂ has higher boiling point than water.
Reason : H₂O₂ has stronger dipole-dipole interactions than that shown by water.

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

B
B. If both assertion and reason are true but reason is not the correct explanation of assertion

C
C. If assertion is true but reason is false.

D
D. If both assertion and reason are false.

Solution

H₂O₂ has higher boiling point than water and it is because H₂O₂ is extensively associated by hydrogen bonding than water or it is more hydrogen bonded than is water.