Class 10 Chemistry Worksheet on Chapter 4 Carbon and Its compounds ... - Free Printable
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Step-by-step solution for: Class 10 Chemistry Worksheet on Chapter 4 Carbon and Its compounds ...
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Show Answer Key & Explanations
Step-by-step solution for: Class 10 Chemistry Worksheet on Chapter 4 Carbon and Its compounds ...
Let’s solve each question one by one with clear explanations.
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Q-1: Identify the unsaturated compounds in the following
a) Chloroprene
b) Butyne
c) Iodopropane
d) Ethane
✔ Answer: a) Chloroprene, b) Butyne
🔹 Explanation:
Unsaturated compounds contain double or triple bonds between carbon atoms (C=C or C≡C).
- Chloroprene – This is 2-chloro-1,3-butadiene. It has two double bonds → unsaturated.
- Butyne – Contains a triple bond (C≡C) → unsaturated.
- Iodopropane – Single bonds only (C–C and C–I) → saturated.
- Ethane – Only single bonds (C–C) → saturated.
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Q-2: Which of the following hydrocarbons undergo addition reactions?
C₂H₆, C₃H₈, C₂H₂, C₂H₄, C₄H₁₀, C₆H₆, C₃H₄
✔ Answer: C₂H₂, C₂H₄, C₃H₄, C₆H₆
🔹 Explanation:
Addition reactions are characteristic of unsaturated hydrocarbons — those with double or triple bonds.
Let’s analyze each:
- C₂H₆ (ethane) → saturated alkane → no
- C₃H₈ (propane) → saturated alkane → no
- C₂H₂ (acetylene) → alkyne (triple bond) → yes
- C₂H₄ (ethylene) → alkene (double bond) → yes
- C₄H₁₀ (butane) → saturated alkane → no
- C₆H₆ (benzene) → aromatic, but still undergoes addition under certain conditions (e.g., hydrogenation), though it prefers substitution. In Class 10 context, it’s often considered to undergo addition → yes
- C₃H₄ (propyne or allene) → alkyne/unsaturated → yes
So, unsaturated ones = C₂H₂, C₂H₄, C₃H₄, C₆H₆
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Q-3: Which of the following is the electron dot structure of the N₂O molecule?
Options:
(a) :N≡N=O:
(b) :N—N=O:
(c) :N=N=O:
(d) :N≡N⁺—O⁻:
✔ Answer: (d) :N≡N⁺—O⁻:
🔹 Explanation:
Nitrous oxide (N₂O) has a linear structure. The most stable Lewis structure has resonance, but the major contributor is:
N≡N⁺—O⁻
→ Central N is bonded to terminal N via triple bond and to O via single bond.
→ Oxygen carries a negative charge, central N carries positive charge.
This satisfies octet rule and minimizes formal charges.
Option (d) correctly shows this resonance form with charges.
Other options:
- (a) No charges shown → incomplete
- (b) Single bond between N’s → too weak
- (c) Double bonds only → doesn’t account for formal charges
So, (d) is correct.
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Q-4: Carbon (Group 14) forms compounds with:
a) Chlorine (Group 17)
b) Sulphur (Group 16)
✔ Answer:
a) Carbon tetrachloride (CCl₄)
b) Carbon disulfide (CS₂)
🔹 Explanation:
Carbon forms covalent compounds with non-metals.
- With chlorine (halogen): CCl₄ — tetrahedral, covalent.
- With sulfur: CS₂ — linear, analogous to CO₂.
Both are common examples taught in Class 10.
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Q-5: Name the following compounds:
(i) CH₃—CH₂—Br
(ii) H—C=O
(iii) H—C—C—C—C=C—H
| | | |
H H H H
*(Structure drawn as 5-carbon chain with double bond at end)*
✔ Answer:
(i) Bromoethane
(ii) Methanal (or Formaldehyde)
(iii) Pent-1-ene
🔹 Explanation:
(i) CH₃CH₂Br → 2 carbons + Br on terminal → Bromoethane
(ii) H—C=O → Aldehyde group with 1 carbon → Methanal
(iii) Structure:
H–C–C–C–C=C–H
| | | |
H H H H
That’s 5 carbons, double bond between C4–C5 → so numbering from right gives double bond at C1 → Pent-1-ene
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Q-6: Give reasons why:
a) Despite the fact that candle wax is composed of saturated hydrocarbons, it produces a yellow luminous flame.
b) Cooking oil decolorizes bromine water but not kerosene oil.
✔ Answers:
a) Candle wax is made of long-chain saturated hydrocarbons (like paraffin). When burned, if there is insufficient oxygen, incomplete combustion occurs. This leads to formation of carbon particles (soot) which get heated and glow → producing yellow luminous flame.
Even saturated hydrocarbons can give luminous flame under incomplete combustion.
b) Cooking oil contains unsaturated fatty acids (with C=C bonds), which react with bromine water via addition reaction, decolorizing it (orange → colorless).
Kerosene oil is mostly saturated hydrocarbons, so it does not react with bromine water → no decolorization.
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Q-7: Which of the following can be used to test the acidic nature of ethanol?
*(Note: The question doesn't list options, but we can infer what is expected.)*
✔ Answer: Blue litmus paper or sodium carbonate/bicarbonate test
🔹 Explanation:
Ethanol (C₂H₅OH) is very weakly acidic (pKa ~15.9), much weaker than water. It does not turn blue litmus red like strong acids do.
However, to test its acidic nature:
- It reacts with sodium metal to produce hydrogen gas:
2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑
*(This shows acidic H, but not "acidic nature" like mineral acids)*
- It does NOT react with Na₂CO₃ or NaHCO₃ (unlike carboxylic acids).
So strictly speaking, ethanol does not show typical acidic behavior like turning litmus red or reacting with carbonates.
➡️ If the question expects an answer, perhaps it's a trick — ethanol is not acidic enough to be tested by usual acid tests.
But if forced to choose, sodium metal test can show it has acidic H.
*Note: Sometimes questions mistakenly imply ethanol is acidic — but in reality, it’s very weakly acidic.*
✔ Best practical test: Reaction with sodium metal → evolution of H₂ gas.
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Q1: a, b
Q2: C₂H₂, C₂H₄, C₃H₄, C₆H₆
Q3: (d)
Q4: a) CCl₄, b) CS₂
Q5: (i) Bromoethane, (ii) Methanal, (iii) Pent-1-ene
Q6:
a) Incomplete combustion → soot → yellow flame
b) Cooking oil has unsaturation → decolorizes Br₂; kerosene is saturated → no reaction
Q7: Sodium metal (to test acidic H); ethanol does not turn litmus red or react with carbonates.
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Let me know if you want diagrams or further clarification!
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Q-1: Identify the unsaturated compounds in the following
a) Chloroprene
b) Butyne
c) Iodopropane
d) Ethane
✔ Answer: a) Chloroprene, b) Butyne
🔹 Explanation:
Unsaturated compounds contain double or triple bonds between carbon atoms (C=C or C≡C).
- Chloroprene – This is 2-chloro-1,3-butadiene. It has two double bonds → unsaturated.
- Butyne – Contains a triple bond (C≡C) → unsaturated.
- Iodopropane – Single bonds only (C–C and C–I) → saturated.
- Ethane – Only single bonds (C–C) → saturated.
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Q-2: Which of the following hydrocarbons undergo addition reactions?
C₂H₆, C₃H₈, C₂H₂, C₂H₄, C₄H₁₀, C₆H₆, C₃H₄
✔ Answer: C₂H₂, C₂H₄, C₃H₄, C₆H₆
🔹 Explanation:
Addition reactions are characteristic of unsaturated hydrocarbons — those with double or triple bonds.
Let’s analyze each:
- C₂H₆ (ethane) → saturated alkane → no
- C₃H₈ (propane) → saturated alkane → no
- C₂H₂ (acetylene) → alkyne (triple bond) → yes
- C₂H₄ (ethylene) → alkene (double bond) → yes
- C₄H₁₀ (butane) → saturated alkane → no
- C₆H₆ (benzene) → aromatic, but still undergoes addition under certain conditions (e.g., hydrogenation), though it prefers substitution. In Class 10 context, it’s often considered to undergo addition → yes
- C₃H₄ (propyne or allene) → alkyne/unsaturated → yes
So, unsaturated ones = C₂H₂, C₂H₄, C₃H₄, C₆H₆
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Q-3: Which of the following is the electron dot structure of the N₂O molecule?
Options:
(a) :N≡N=O:
(b) :N—N=O:
(c) :N=N=O:
(d) :N≡N⁺—O⁻:
✔ Answer: (d) :N≡N⁺—O⁻:
🔹 Explanation:
Nitrous oxide (N₂O) has a linear structure. The most stable Lewis structure has resonance, but the major contributor is:
N≡N⁺—O⁻
→ Central N is bonded to terminal N via triple bond and to O via single bond.
→ Oxygen carries a negative charge, central N carries positive charge.
This satisfies octet rule and minimizes formal charges.
Option (d) correctly shows this resonance form with charges.
Other options:
- (a) No charges shown → incomplete
- (b) Single bond between N’s → too weak
- (c) Double bonds only → doesn’t account for formal charges
So, (d) is correct.
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Q-4: Carbon (Group 14) forms compounds with:
a) Chlorine (Group 17)
b) Sulphur (Group 16)
✔ Answer:
a) Carbon tetrachloride (CCl₄)
b) Carbon disulfide (CS₂)
🔹 Explanation:
Carbon forms covalent compounds with non-metals.
- With chlorine (halogen): CCl₄ — tetrahedral, covalent.
- With sulfur: CS₂ — linear, analogous to CO₂.
Both are common examples taught in Class 10.
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Q-5: Name the following compounds:
(i) CH₃—CH₂—Br
(ii) H—C=O
(iii) H—C—C—C—C=C—H
| | | |
H H H H
*(Structure drawn as 5-carbon chain with double bond at end)*
✔ Answer:
(i) Bromoethane
(ii) Methanal (or Formaldehyde)
(iii) Pent-1-ene
🔹 Explanation:
(i) CH₃CH₂Br → 2 carbons + Br on terminal → Bromoethane
(ii) H—C=O → Aldehyde group with 1 carbon → Methanal
(iii) Structure:
H–C–C–C–C=C–H
| | | |
H H H H
That’s 5 carbons, double bond between C4–C5 → so numbering from right gives double bond at C1 → Pent-1-ene
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Q-6: Give reasons why:
a) Despite the fact that candle wax is composed of saturated hydrocarbons, it produces a yellow luminous flame.
b) Cooking oil decolorizes bromine water but not kerosene oil.
✔ Answers:
a) Candle wax is made of long-chain saturated hydrocarbons (like paraffin). When burned, if there is insufficient oxygen, incomplete combustion occurs. This leads to formation of carbon particles (soot) which get heated and glow → producing yellow luminous flame.
Even saturated hydrocarbons can give luminous flame under incomplete combustion.
b) Cooking oil contains unsaturated fatty acids (with C=C bonds), which react with bromine water via addition reaction, decolorizing it (orange → colorless).
Kerosene oil is mostly saturated hydrocarbons, so it does not react with bromine water → no decolorization.
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Q-7: Which of the following can be used to test the acidic nature of ethanol?
*(Note: The question doesn't list options, but we can infer what is expected.)*
✔ Answer: Blue litmus paper or sodium carbonate/bicarbonate test
🔹 Explanation:
Ethanol (C₂H₅OH) is very weakly acidic (pKa ~15.9), much weaker than water. It does not turn blue litmus red like strong acids do.
However, to test its acidic nature:
- It reacts with sodium metal to produce hydrogen gas:
2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑
*(This shows acidic H, but not "acidic nature" like mineral acids)*
- It does NOT react with Na₂CO₃ or NaHCO₃ (unlike carboxylic acids).
So strictly speaking, ethanol does not show typical acidic behavior like turning litmus red or reacting with carbonates.
➡️ If the question expects an answer, perhaps it's a trick — ethanol is not acidic enough to be tested by usual acid tests.
But if forced to choose, sodium metal test can show it has acidic H.
*Note: Sometimes questions mistakenly imply ethanol is acidic — but in reality, it’s very weakly acidic.*
✔ Best practical test: Reaction with sodium metal → evolution of H₂ gas.
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✔ Final Summary of Answers:
Q1: a, b
Q2: C₂H₂, C₂H₄, C₃H₄, C₆H₆
Q3: (d)
Q4: a) CCl₄, b) CS₂
Q5: (i) Bromoethane, (ii) Methanal, (iii) Pent-1-ene
Q6:
a) Incomplete combustion → soot → yellow flame
b) Cooking oil has unsaturation → decolorizes Br₂; kerosene is saturated → no reaction
Q7: Sodium metal (to test acidic H); ethanol does not turn litmus red or react with carbonates.
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Let me know if you want diagrams or further clarification!
Parent Tip: Review the logic above to help your child master the concept of carbon compounds worksheet.
