The Question is from neet-chemistry haloalkanes-haloarenes , and it was created by the author P SRAVAN KUMAR

Question

General formula for arenes is:

P SRAVAN KUMAR · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
	**Primary Concept**: General formula of arenes
	**Related Topics**: Hydrocarbons, Aromatic compounds, Degree of unsaturation
	**Prerequisites**: Basic understanding of organic nomenclature and hydrocarbon structure
## SOLUTION PATHWAY
**Given Information**:
	General formula for arenes is required
	Options provided are different possible general formulas
**Method & Steps**:
	1. Recall the basic structure of an arene. Arenes are cyclic hydrocarbons with alternating single and double bonds (i.e., benzene and its derivatives).
		Reasoning: The basic structure of arenes contains a benzene ring. Each benzene ring has 6 carbon atoms and a specific number of hydrogen atoms due to the cyclic structure and alternating double bonds
	2. The general formula for an alkane is $C_nH_{2n+2}$. For each ring or double bond, 2 hydrogens are removed. Benzene has 3 double bonds and one ring. Thus, it has 4 degrees of unsaturation. 
		Working: Therefore, the general formula for an arene with y number of benzene rings will have 6y fewer hydrogen atoms than the corresponding alkane.The general formula can be expressed as ${{m{C}}_n}{{m{H}}_{2n+2-6y-2(y-1)}}$ or ${{m{C}}_n}{{m{H}}_{2n-6y}}$.
	3. Select the option that matches the derived general formula.
		Result: The correct formula is ${{m{C}}_n}{{m{H}}_{2n - 6y}}$
 ## OPTION ANALYSIS
[A] :x: ${{m{C}}_n}{{m{H}}_{2n + 6}}$ - This formula would represent an alkane with 3 extra hydrogen atoms per carbon and is not the general formula for arenes.
[B] :x: ${{m{C}}_n}{{m{H}}_{2n + 6y}}$ - This formula implies an increase in the number of hydrogen atoms with the number of benzene rings, which is not the case.
[C] :x: ${{m{C}}_n}{{m{H}}_{2n}}$ - This formula is the general formula for alkenes or cycloalkanes, which is incorrect for arenes.
[D] ✓: ${{m{C}}_n}{{m{H}}_{2n - 6y}}$ - This is the correct general formula for arenes, where 'y' represents the number of benzene rings.
 ## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing the formula of arenes with that of alkanes or alkenes: Remember that arenes have a benzene ring, which has fewer hydrogens due to the double bonds and ring structure.
		2. Incorrectly calculating the number of hydrogen atoms removed for each ring or double bond: Each double bond or ring removes 2 hydrogen atoms from the alkane formula.
	**Quick Tips**:
		1. Remember that the simplest arene, benzene (C6H6), has 6 fewer hydrogens than the corresponding alkane (C6H14).
		2. Use the concept of degree of unsaturation to determine the general formula of different types of hydrocarbons.

P SRAVAN KUMAR · Answer

${{\rm{C}}_n}{{\rm{H}}_{2n + 6}}$

P SRAVAN KUMAR · Answer

${{\rm{C}}_n}{{\rm{H}}_{2n + 6y}}$

P SRAVAN KUMAR · Answer

${{\rm{C}}_n}{{\rm{H}}_{2n}}$

P SRAVAN KUMAR · Answer

The correct Option is "${{\rm{C}}_n}{{\rm{H}}_{2n - 6y}}$"

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