(A) (i) Define a homologous series of carbon compounds.
(ii) Why is the melting and boiling points of \(C_4H_8\) higher than that of \(C_3H_6\) or \(C_2H_4\)?
(iii) Why do we NOT see any gradation in chemical properties of a homologous series compounds?
(iv) Write the name and structures of (i) aldehyde and (ii) ketone with molecular formula \(C_3H_6O\).OR
(B) (i) Write the name and structure of an organic compound ‘X’ having two carbon atoms in its molecule and its name is suffixed with ‘-ol’.
(ii) What happens when ‘X’ is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation for the reaction stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction.
(iii) Name and draw the electron dot structure of hydrocarbon produced in the above reaction.
(ii) Why is the melting and boiling points of \(C_4H_8\) higher than that of \(C_3H_6\) or \(C_2H_4\)?
(iii) Why do we NOT see any gradation in chemical properties of a homologous series compounds?
(iv) Write the name and structures of (i) aldehyde and (ii) ketone with molecular formula \(C_3H_6O\).
OR
(B) (i) Write the name and structure of an organic compound ‘X’ having two carbon atoms in its molecule and its name is suffixed with ‘-ol’.(ii) What happens when ‘X’ is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation for the reaction stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction.
(iii) Name and draw the electron dot structure of hydrocarbon produced in the above reaction.
Solution and Explanation
(A) i. A homologous series is a group of organic compounds with the same general formula, similar chemical properties, and successive members differing by a \(-\text{CH}_2\) group. Example: Alkanes (\(\text{C}_n\text{H}_{2n+2}\)), alkenes (\(\text{C}_n\text{H}_{2n}\)), and alcohols (\(\text{C}_n\text{H}_{2n+1}\text{OH}\)).
ii. Chemical properties are determined by the functional group, which is constant in a homologous series. Hence, compounds of the series exhibit similar reactivity, with no gradation in chemical properties.
iii. Aldehyde: Propanal
Structure: \(\text{CH}_3\text{-CH}_2\text{-CHO}\)
Ketone: Propanone (acetone)
Structure: \(\text{CH}_3\text{-CO-CH}_3\)
(B) i. Solution: The compound is ethanol.
Structure: \(\text{CH}_3\text{-CH}_2\text{-OH}\)
ii. When ethanol (\(\text{CH}_3\text{-CH}_2\text{-OH}\)) is heated with concentrated \(\text{H}_2\text{SO}_4\) at 443 K, it undergoes dehydration to form ethene (\(\text{C}_2\text{H}_4\)).
Reaction: \(\text{CH}_3\text{-CH}_2\text{-OH} \rightarrow \text{C}_2\text{H}_4 + \text{H}_2\text{O}\)
Conditions: Temperature of 443 K, excess concentrated \(\text{H}_2\text{SO}_4\)
iii. The hydrocarbon produced is ethene (\(\text{C}_2\text{H}_4\)).
Top Questions on Organic Chemistry
- Given below are two statements: Statement I: One mole of propyne reacts with excess of sodium to liberate half a mole of H₂ gas. Statement II: Four g of propyne reacts with NaNH₂ to liberate NH₃ gas which occupies 224 mL at STP. In the light of the above statements, choose the most appropriate answer from the options given below:
- JEE Main - 2025
- Chemistry
- Organic Chemistry
For the thermal decomposition of \( N_2O_5(g) \) at constant volume, the following table can be formed, for the reaction mentioned below: \[ 2 N_2O_5(g) \rightarrow 2 N_2O_4(g) + O_2(g) \] Given: Rate constant for the reaction is \( 4.606 \times 10^{-2} \text{ s}^{-1} \).
- JEE Main - 2025
- Chemistry
- Organic Chemistry
- Identify A and B in each of the following reaction sequence:
(a) \[ CH_3CH_2Cl \xrightarrow{NaCN} A \xrightarrow{H_2/Ni} B \]
(b) \[ C_6H_5NH_2 \xrightarrow{NaNO_2/HCl} A \xrightarrow{C_6H_5NH_2} B \]- CBSE CLASS XII - 2025
- Chemistry
- Organic Chemistry
A hydrocarbon which does not belong to the same homologous series of carbon compounds is
- CBSE Class X - 2025
- Science
- Organic Chemistry
- Carbohydrates are polyhydroxy aldehydes or ketones that represent enormous structural diversity in terms of the arrangement of atoms in space, resulting in hundreds of stereoisomers. Although the chemical properties of most stereoisomers may not be very different, their metabolic rate and utilization in biological systems is significantly different and known to influence the overall carbohydrate metabolism. Structural variants, which arise due to a different arrangement of atoms in three-dimensional space are known as stereoisomers. The number of stereoisomers can be theoretically estimated by using the formula 2n, where ‘n’ is the number of stereocenters or asymmetric (chiral) carbon atoms in a molecule. Out of these stereoisomers, there are some structures, which are mirror images of each other, and they are referred to as enantiomers.
- CBSE CLASS XII - 2025
- Chemistry
- Organic Chemistry
Questions Asked in CBSE X exam
- Name the type of lenses required by the persons for the correction of their defect of vision called presbyopia. Write the structure of the lenses commonly used for the correction of this defect giving reason for such designs.
How is the brain protected in our body?
- CBSE Class X - 2025
- Brain Structure
- Describe the historical factors that contributed to the emergence of nationalist tensions in the Balkans.
- CBSE Class X - 2025
- The Rise of Nationalism in Europe
आप नव्या / भव्य हैं। विद्यालय में नामांकन के समय आपकी जन्मतिथि गलत दर्ज हो गई है। दसवीं के पंजीकरण से पहले आप इसे सुधरवाना चाहते हैं। जन्मतिथि में सुधार हेतु निवेदन करते हुए प्रधानाचार्य को लगभग 80 शब्दों में एक ई-मेल लिखिए।
- CBSE Class X - 2025
- पत्र लेखन
आप अदिति / आदित्य हैं। आपकी दादीजी को खेलों में अत्यधिक रुचि है। ओलंपिक खेल-2024 में भारत के प्रदर्शन के बारे में जानकारी देते हुए लगभग 100 शब्दों में पत्र लिखिए।
- CBSE Class X - 2025
- पत्र लेखन