Carbon & its Compounds - 2 - Free MCQ Test with solutions for UPSC Sci

The saponification reaction is the hydrolysis of an ester in the presence of a strong base (such as NaOH) to produce a carboxylate salt (soap) and an alcohol.

Option D:

This correctly represents saponification, where an ester reacts with NaOH to form a salt of the acid and an alcohol.

When ethanol is heated with concentrated sulphuric acid at 443 K, dehydration takes place and ethene is formed. In this reaction concentrated sulphuric acid acts as a dehydrating agent.
CH₃-CH₂-OH → (H₂SO₄ + heat) → CH₂=CH₂ + H₂O

Compounds made of carbon and hydrogen that contain double or triple bonds are known as unsaturated hydrocarbons.

• Examples of unsaturated hydrocarbons include those with alkenes (double bonds) and alkynes (triple bonds).

The smallest alkyne contains two carbon atoms with a triple bond between them and is called ethyne (C₂H₂).

CH₃CH₂OH is present in alcoholic drinks. It is known as ethanol which is prepared by fermentation of sugar (molasses).

- Straight chain compounds are one of the types of isomers of organic compounds in which there is no substituent attached on the parent hydrocarbon chain.
- Let’s have a look at the given compounds in the question.
- First compound is,

- Now, we need to count the total number of carbon atoms present in this compound. The total number of carbon atoms present in this compound is five. Also, the longest continuous hydrocarbon chain present in the compound is pentane only. There are no substituents attached on the chain. Therefore, this is a straight chain compound.
- Second compound is,

- In this compound, the total number of carbon atoms is six and but, the longest continuous hydrocarbon chain is pentane. There is one methyl substituent attached to the second carbon atom in the chain. Therefore, this compound is not a straight chain compound. This compound is a branched chain compound, iso-hexane.
- Third compound is,

- In this compound, the total number of carbon atoms is six and also, the longest continuous hydrocarbon chain is hexane. There are no substituents attached on the chain. Therefore, this compound is a straight chain compound, n-hexane.
- Fourth compound is,

- In this compound, the total number of carbon atoms is six and also, the longest continuous hydrocarbon chain is hexane. There are no substituents attached on the chain. Therefore, this compound is a straight chain compound, n-hexane.
- Therefore, compound (B) iso-hexane is not a straight chain compound.

Therefore, the correct option is option (d).

Note:
Don’t get confused that the term ‘straight’ indicates the number of carbon present in one line. That is a common mistake. Straight chain means number of carbon atoms forming a long continuous chain. It can be represented in many ways, zig-zag, or vertically, or horizontally, etc. Be thorough with this minor concept.

Ethanol reacts with sodium metal to produce:

• C₂H₅OH (ethanol) reacts with sodium (Na).
• This reaction forms C₂H₅ONa (sodium ethoxide).
• Additionally, H₂ (hydrogen gas) is released.

The chemical equation is:

C₂H₅OH + Na → C₂H₅ONa + H₂

Compounds (a), (b) and (c) are saturated hydrocarbons but compound (d) is unsaturated. Compounds of the same homologous series have the same general formula.

The heteroatoms in the compound are oxygen (O) and chlorine (Cl), which are different from carbon (C) and hydrogen (H).

• The correct answer is option D.
• Option D includes both heteroatoms.

After sharing four electrons with four univalent atoms, carbon has 6 + 4 = 10 electrons.
Neon also contains 10 electrons

Vinegar is a diluted solution of acetic acid in water. It’s composition is 5% - 8% of acetic acid in water.

It contains a total of three carbon atoms with an aldehyde group. Propane + al = propanal.

The equation for the reaction between sodium and ethanol can be written as:

2CH₃​CH₂​OH+2Na→2CH_3​CH_2​ONa+H_2​

Therefore, the products formed are sodium ethoxide and hydrogen