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Diagram showing different hydrocarbon structures with their correct chemical names.

Structural formulas of various organic compounds including heptane, hexane, nonane, undecane, cycloheptane, cyclohexane, and decane, each labeled with its name.

Structural formulas of various organic compounds including heptane, hexane, nonane, undecane, cycloheptane, cyclohexane, and decane, each labeled with its name.

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Show Answer Key & Explanations Step-by-step solution for: Naming Alkanes with Practice Problems - Chemistry Steps
Let’s go through each structure one by one and check if the name given matches the actual molecule.

We’ll count the longest continuous carbon chain (for alkanes) or the ring size (for cycloalkanes), and make sure the name reflects that.

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a) Structure: A 7-carbon straight chain with two methyl groups attached — but wait, let’s trace the longest chain.

Actually, if you look closely, the longest chain is not 7 carbons. Let’s number it:

Start from left: C1–C2–C3–C4–C5–C6–C7? But at C3 and C4 there are branches. Actually, if you go from the top branch down to the right, you can get a longer chain!

Wait — let’s redraw mentally:

The main chain should be the longest possible. In this case, if you start from the leftmost end, go to the first branch (methyl on C3), then continue to the next branch (methyl on C4), then to the right end — that’s still 7 carbons? Wait no — actually, if you take the path that goes up over the branches, you might get more.

Actually, let’s count carefully:

Left end → CH₃–CH₂–CH(CH₃)–CH(CH₃)–CH₂–CH₂–CH₃

That’s 7 carbons in the main chain? Yes — positions 3 and 4 have methyl groups. So total carbons = 7 + 2 = 9? No — the base chain is heptane (7 carbons), with two methyl substituents → so it’s a dimethylheptane.

But the label says “Heptane” — which implies just the straight-chain alkane with 7 carbons, no branches.

This molecule has branches → so it’s NOT heptane. It’s a substituted heptane.

So a) is incorrectly labeled.

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b) Structure: Cyclopentane ring attached to a 6-carbon chain.

Label says “Hexane”.

Hexane means a straight-chain alkane with 6 carbons.

Here we have a cyclopentane (5-membered ring) + hexyl group? The chain attached is 6 carbons long? Let’s see:

Ring – CH₂–CH₂–CH₂–CH₂–CH₂–CH₃ → that’s 6 carbons in the chain.

But the whole molecule is not hexane — it’s (cyclopentyl)hexane or something like that.

“Hexane” alone refers only to CH₃(CH₂)₄CH₃ — no rings.

So b) is incorrectly labeled.

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c) Label: Nonane

Structure: Looks like a branched chain. Let’s find the longest chain.

Start from top left: go right, down, right, down, right — that’s 9 carbons? Let’s count:

Assume the backbone is: C1–C2–C3–C4–C5–C6–C7–C8–C9

With branches on C3 (isopropyl?), C5 (methyl?), C7 (isopropyl?) — wait, need to trace properly.

Actually, looking at the drawing: it seems the longest chain is indeed 9 carbons, with several alkyl groups attached.

So if the longest continuous chain is 9 carbons, then calling it “Nonane” is acceptable as the parent name — though strictly speaking, it should be named with substituents (like 3-isopropyl-5-methyl-7-(1-methylethyl)nonane or something). But often in such exercises, if the base chain is correct, they accept it.

But wait — is the longest chain really 9?

Let me try to trace: Start from bottom right: go up, left, up, left, up, left, up, left — that’s 8? Hmm.

Actually, better way: count all atoms in the longest unbroken chain.

Looking at the structure again — it appears the horizontal chain has 9 carbons, with branches sticking off. So yes, parent chain is nonane.

So c) is correctly labeled — assuming we’re just identifying the parent chain.

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d) Label: Undecane

Undecane = 11 carbons in a row.

Structure: Multiple branches. Let’s find longest chain.

Start from far left: go right, down, right, up, right, down, right — let’s count:

C1–C2–C3–C4–C5–C6–C7–C8–C9–C10–C11? Possibly.

Actually, tracing: leftmost CH₃–CH–(branch)–CH₂–CH–(branch)–CH₂–CH–(branch)–CH₂–CH₂–CH₃

If we ignore branches, the backbone could be 11 carbons.

Yes — seems like the longest chain is 11 carbons. So undecane is correct as parent name.

So d) is correctly labeled.

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e) Label: Nonane

Structure: Branched chain. Find longest chain.

Start from left: CH₃–CH₂–CH–(branch)–CH₂–CH₂–CH–(branch)–CH₂–CH₃

Count: 1-2-3-4-5-6-7-8-9 → 9 carbons.

Branches on C3 and C7.

So parent chain is nonane → correct.

e) is correctly labeled.

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f) Label: Cycloheptane

Structure: 7-membered ring? Let’s count the ring atoms.

It’s a ring with 7 carbons? Drawn as a heptagon? Actually, in the image, it looks like a 7-sided ring? Wait — standard notation: a polygon with n sides = cycloalkane with n carbons.

In f), the ring has 7 vertices → cycloheptane.

Then attached to it is a chain: –CH₂–CH₂–CH–(CH(CH₃)₂)–CH₂–CH₃? Something like that.

But the label is “Cycloheptane” — which would imply just the ring, no substituents.

This molecule has a substituent → so it’s not pure cycloheptane; it’s (substituted)cycloheptane.

So f) is incorrectly labeled — because it’s not just cycloheptane; it’s a derivative.

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g) Label: Cyclohexane

Structure: 6-membered ring with substituents.

Again, cyclohexane means just the ring, C₆H₁₂.

Here, the ring has three alkyl groups attached → so it’s a substituted cyclohexane.

Thus, g) is incorrectly labeled.

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h) Label: Decane

Decane = 10-carbon straight chain.

Structure: Highly branched. Let’s find longest chain.

Start from top left: go right, down, right, down, right, up, right — let’s count:

Possibly: C1–C2–C3–C4–C5–C6–C7–C8–C9–C10 → yes, 10 carbons.

Even with branches, if the longest continuous chain is 10, then decane is correct as parent name.

So h) is correctly labeled.

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i) Label: Heptane

Structure: Branched chain. Longest chain?

Start from left: CH₃–CH₂–CH₂–CH–(branch)–CH₂–CH–(branch)

Chain: 1-2-3-4-5-6-7 → 7 carbons.

Branches on C4 and C6.

So parent chain is heptane → correct.

i) is correctly labeled.

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Now, summarize which ones are correctly labeled:

Correctly labeled (parent chain matches):

- c) Nonane
- d) Undecane
- e) Nonane
- h) Decane
- i) Heptane

Incorrectly labeled:

- a) Heptane (should be dimethylheptane or similar)
- b) Hexane (has cyclopentyl group)
- f) Cycloheptane (has substituent)
- g) Cyclohexane (has substituents)

So the question is — what exactly is being asked? The user didn’t specify, but since it’s a homework problem and the image shows structures with names, likely the task is to identify which names are correct.

But the original instruction says: “Solve the problem accurately.” And the options are ExplainAnswer=false, etc., so probably we just need to list which are correct.

Wait — perhaps the task is to select all that are correctly named? Or maybe to point out errors?

Since no specific question was stated, but in context of such images, usually the task is: “Which of these are correctly named?”

Given that, I’ll assume we need to list the letters where the name matches the structure (i.e., the parent chain/ring is correctly identified).

From above:

Correct: c, d, e, h, i

Incorrect: a, b, f, g

But let’s double-check a) again.

In a): The structure is:

CH₃–CH₂–CH(CH₃)–CH(CH₃)–CH₂–CH₂–CH₃

Longest chain: if you go from left to right, it’s 7 carbons. You cannot get a longer chain by going through branches — because branches are methyls (only 1 carbon). So longest chain is 7 → heptane is correct as parent name.

Oh! I made a mistake earlier.

In a), even though there are branches, the longest continuous chain is still 7 carbons. So naming it “Heptane” as the base is acceptable — though technically it should be 3,4-dimethylheptane, but if the exercise is just about identifying the parent chain length, then “Heptane” indicates the base chain has 7 carbons.

Similarly for others.

In many introductory contexts, when they write “Heptane” under a branched structure, they mean the parent chain is heptane — not that it’s unbranched.

So perhaps all except b, f, g are correct? Because b has a ring, f and g have rings with substituents, while a,c,d,e,h,i are all acyclic with correct parent chain lengths.

Let’s reevaluate with that mindset.

Standard rule: For naming, we identify the longest carbon chain (or largest ring) as the parent.

So:

- a) Longest chain: 7 carbons → Heptane
- b) Has a ring + chain → not hexane (which is acyclic)
- c) Longest chain: 9 carbons → Nonane
- d) Longest chain: 11 carbons → Undecane
- e) Longest chain: 9 carbons → Nonane
- f) Ring is 7 carbons, but has substituent → should be named as substituted cycloheptane, not just "Cycloheptane"
- g) Ring is 6 carbons, with substituents → not just "Cyclohexane"
- h) Longest chain: 10 carbons → Decane
- i) Longest chain: 7 carbons → Heptane

So incorrect are only b, f, g.

Why? Because b is not an alkane called "hexane" — it's a cycloalkyl-substituted alkane. f and g are substituted cycloalkanes, so their names should reflect that (e.g., "alkylcycloheptane"), not just the ring name.

Whereas for a,c,d,e,h,i, even though branched, the parent chain name is correctly given.

Therefore, the correctly labeled ones are: a, c, d, e, h, i

Incorrect: b, f, g

But let’s confirm b): The structure is cyclopentyl attached to a hexyl group. The IUPAC name would be (cyclopentyl)hexane or 1-cyclopentylhexane. Calling it "Hexane" is wrong because hexane specifically means CH3(CH2)4CH3.

Similarly, f) is not cycloheptane — it’s, say, 1-(1,2-dimethylpropyl)cycloheptane or something — definitely not just "Cycloheptane".

Same for g).

So final decision:

Correctly named (parent identifier matches): a, c, d, e, h, i

Incorrectly named: b, f, g

Now, since the problem likely expects us to identify which are correct, and given the format, I think the answer is to list the correct ones.

But the user didn't specify the exact question. However, in such multiple-choice style images, often the task is to pick the correct ones.

Perhaps the problem is: "Which of the following are correctly named?" and we need to select all that apply.

Given that, I'll provide the list of correctly labeled structures.

Final Answer: a, c, d, e, h, i
Parent Tip: Review the logic above to help your child master the concept of naming alkanes worksheet with answers.
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