Carbon And Its Compounds - Class 10 MCQ

Explanation:
The correct statements for carbon compounds are as follows:
B: Most carbon compounds are poor conductors of electricity.
- Carbon compounds are usually covalent compounds, which means they have shared electron pairs between atoms.
- Covalent compounds do not have free electrons that can move and carry an electric charge, so they are generally poor conductors of electricity.
C: Force of attraction between molecules of carbon compounds is not very strong.
- Carbon compounds are formed by carbon atoms bonding with other elements like hydrogen, oxygen, nitrogen, etc.
- These bonds are typically covalent bonds, which are formed by the sharing of electrons.
- Covalent bonds are relatively weaker compared to ionic or metallic bonds, which means the force of attraction between molecules of carbon compounds is not very strong.
Therefore, the correct statements for carbon compounds are B and C. Most carbon compounds are poor conductors of electricity, and the force of attraction between molecules of carbon compounds is not very strong.

Answer:

Homologous series:

• Homologous series is a family of organic compounds that have similar chemical properties and a gradual increase in molecular structure.


• The members of a homologous series have the same functional group and a similar general formula.

Classification of organic compounds:

• Alkanes: Alkanes are hydrocarbons that only contain single bonds between carbon atoms. The general formula for alkanes is C_nH_2n+2.


• Alkenes: Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. The general formula for alkenes is C_nH_2n.


• Alkynes: Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. The general formula for alkynes is C_nH_2n-2.


• Cycloalkanes: Cycloalkanes are hydrocarbons that form a closed ring structure. They have the general formula C_nH_2n.

Identification of C₃H₈:

• C₃H₈ represents a hydrocarbon with 3 carbon atoms.


• Using the general formulas for each class of organic compounds, we can determine that C₃H₈ fits the formula C_nH_2n+2 for alkanes.

Conclusion:

C₃H₈ belongs to the homologous series of alkanes as it follows the general formula for alkanes, C_nH_2n+2.

To determine the number of isomers of pentane, we need to consider the different ways in which the carbon atoms can be arranged in the molecule. Pentane has the molecular formula C5H12, which means it consists of five carbon atoms and 12 hydrogen atoms.
1. Straight-Chain Isomers: Pentane can exist in a straight-chain structure with all five carbon atoms arranged in a row. This is the most basic and common form of pentane.
2. Branching Isomers: Pentane can also exist in various branching forms where one or more carbon atoms have additional carbon branches attached to them. There are three possible positions for the branching carbon atom in pentane, which are the second, third, and fourth carbon atoms.
Based on these considerations, the number of isomers of pentane is as follows:
- Straight-Chain Isomer: 1
- Branching Isomers: 2 (one branch on the second carbon atom and one branch on the third carbon atom)
- Branching Isomers: 1 (two branches on the second carbon atom)
- Branching Isomers: 0 (two branches on the third carbon atom)
- Branching Isomers: 0 (two branches on the fourth carbon atom)
Therefore, the total number of isomers of pentane is 1 + 2 + 1 + 0 + 0 = 4.
Hence, the correct answer is C: 4.

Explanation:
To determine which of the given compounds will undergo addition reactions, we need to understand what an addition reaction is.
An addition reaction is a type of chemical reaction in which two or more molecules combine to form a larger molecule. It involves the breaking of existing bonds and the formation of new bonds.
Now, let's analyze each compound:
A: CH₄
- Methane is a saturated hydrocarbon. It contains only single bonds between carbon and hydrogen atoms.
- Saturated hydrocarbons do not readily undergo addition reactions because all the carbon atoms are already bonded to the maximum number of hydrogen atoms.
- Therefore, CH₄ will not undergo addition reactions.
B: C₃H₈
- Propane is also a saturated hydrocarbon.
- Like CH₄, C₃H₈ does not have any carbon-carbon double bonds, which are necessary for addition reactions.
- Therefore, C₃H₈ will not undergo addition reactions.
C: C₂H₆
- Ethane is a saturated hydrocarbon.
- It does not have any carbon-carbon double bonds.
- Therefore, C₂H₆ will not undergo addition reactions.
D: C₂H₄
- Ethene is an unsaturated hydrocarbon. It contains a carbon-carbon double bond.
- Unsaturated hydrocarbons are capable of undergoing addition reactions because the double bond can be broken and new bonds can be formed.
- Therefore, C₂H₄ will undergo addition reactions.
In conclusion, the compound that will undergo addition reactions is D: C₂H₄.

Answer:
Ethanol, when completely oxidized, undergoes a series of chemical reactions that result in the formation of carbon dioxide and water. This process is known as complete combustion or oxidation.
The balanced chemical equation for the complete oxidation of ethanol is as follows:
C2H5OH + 3O2 → 2CO2 + 3H2O
Explanation:
- Ethanol (C2H5OH) is a type of alcohol commonly found in alcoholic beverages and industrial products.
- Complete oxidation refers to the reaction that occurs when a substance is burned in the presence of oxygen, resulting in the complete conversion of the substance into its oxidized form.
- In the case of ethanol, the carbon and hydrogen atoms present in the molecule combine with oxygen to form carbon dioxide (CO2) and water (H2O).
- The balanced chemical equation shows that one molecule of ethanol reacts with three molecules of oxygen to produce two molecules of carbon dioxide and three molecules of water.
- This reaction is exothermic, meaning it releases heat energy.
In conclusion, the complete oxidation of ethanol leads to the formation of carbon dioxide and water. Therefore, option B is the correct answer.

To obtain a pleasant smell of ester when heated with ethanol and a small quantity of sulphuric acid, we need to consider the reaction known as esterification. Esterification is the process of combining an alcohol (in this case, ethanol) with an acid (in this case, acetic acid) to form an ester.
Let's evaluate each option and determine which one will give a pleasant smell of ester:
A: CH₃COOH (acetic acid)
- Acetic acid reacts with ethanol to form ethyl acetate, which has a pleasant fruity smell. This option is correct.
B: CH₃CH₂OH (ethanol)
- Ethanol is one of the reactants in the esterification process, but it does not produce a pleasant smell of ester on its own.
C: CH₃OH (methanol)
- Methanol is not involved in the esterification reaction and will not produce a pleasant smell of ester.
D: CH₃CHO (acetaldehyde)
- Acetaldehyde can undergo reactions to form esters, but it does not directly react with ethanol to produce a pleasant smell of ester.
Therefore, the correct answer is option A: CH₃COOH (acetic acid).

Identifying 'A' in the reaction:
The given reaction is:
CH₃COOH + Na₂CO₃ → A + CO₂ + H₂O
To identify 'A', we need to understand the reaction and the products it forms.
Reaction:
CH₃COOH + Na₂CO₃ → A + CO₂ + H₂O
Explanation:
- CH₃COOH is acetic acid.
- Na₂CO₃ is sodium carbonate.
- CO₂ is carbon dioxide.
- H₂O is water.
Products formed:
- CO₂ and H₂O are products of the reaction.
- 'A' is the compound formed when acetic acid (CH₃COOH) reacts with sodium carbonate (Na₂CO₃).
Identifying 'A':
- The compound formed when acetic acid reacts with sodium carbonate is sodium acetate (CH₃COONa).
- Therefore, 'A' in the given reaction is CH₃COONa.
Answer:
The compound 'A' in the given reaction CH₃COOH + Na₂CO₃ → A + CO₂ + H₂O is CH₃COONa.

Explanation:

Structural isomers have the same molecular formula but different structural arrangements. In this case, the molecular formula is C₄H₁₀, which indicates that there are four carbon atoms and ten hydrogen atoms in each isomer.

Option A:

• This structure shows four carbon atoms connected in a straight chain.


• The name of this isomer is n-butane.

Option B:

• This structure shows a branched chain with a methyl group attached to the second carbon atom.


• The name of this isomer is 2-methylpropane or isobutane.

Option C:

• This structure shows a cyclobutane ring with four carbon atoms.


• Cyclobutane is not a structural isomer of butane because it has a different molecular formula, C₄H₈.

Option D:

• This structure shows a cyclobutane ring with four carbon atoms and a methyl group attached to it.


• Similar to option C, this is also not a structural isomer of butane because it has a different molecular formula, C₅H₁₀.

Therefore, the correct structural isomers of butane are options A and B.

Explanation:
1. Ethanol reacts with sodium:
When ethanol (C2H5OH) reacts with sodium (Na), a chemical reaction occurs. The sodium displaces the hydrogen from the hydroxyl group of ethanol, resulting in the formation of a new compound.
2. Formation of sodium ethoxide:
The reaction between ethanol and sodium leads to the formation of sodium ethoxide (C2H5ONa). In this reaction, the sodium atom replaces the hydrogen atom in the hydroxyl group of ethanol, resulting in the formation of sodium ethoxide.
3. Formation of hydrogen gas:
As a byproduct of the reaction, hydrogen gas (H2) is also formed. This occurs when the sodium reacts with the remaining hydroxyl group in ethanol.
4. Overall reaction:
The reaction between ethanol and sodium can be summarized as follows:
Ethanol + Sodium → Sodium Ethoxide + Hydrogen
5. Conclusion:
Based on the given options, the correct answer is option C: sodium ethoxide and hydrogen.