Learning Arc 01 · Read and classify carbon-halogen structures
Explain physical properties from structure
Later reaction choices use local shape and electron distribution, while Board and NCERT property questions require different evidence jobs to stay separate.
Foundation for this Concept12 symbols · 3 recovery lessons · 4 entry checksOpen
Start here: words and symbols used in this Concept
Open only the recovery material you need before the Mystery.
Read these words and symbols first
- bond direction
- one directly bonded atom seen from the selected carbon
- A double-bonded atom is one neighbour direction, although the bond-order total includes two.
- orbital model
- An orbital is a modelled region where an electron is likely to be found.
- It is not a path travelled by an electron.
- The letters s and p name two orbital shapes.
- An s orbital is roughly spherical.
- A p orbital has two lobes.
- A hybrid orbital is a new directional orbital formed by mixing s and p orbitals in this HSC model.
- An unhybridised p orbital is a p orbital left outside that mixing.
- A pi bond is the second part of a double bond formed by sideways overlap of those remaining p orbitals.
- This is a bounded school model.
- It does not draw an electron.s path.
- Deeper theory is deferred.
- tetrahedral
- Four bond directions point towards four corners around one carbon in the accepted three-dimensional model.
- About 109.5 degrees is an idealised model angle, not an exact value for every molecule.
- trigonal planar
- Three bond directions lie around one carbon in one plane in the accepted model.
- About 120 degrees is an idealised model angle.
- sp³ carbon
- Read sp³ as s-p-three.
- One s orbital and three p orbitals mix.
- They form four equivalent sp³ hybrid orbitals.
- The four directions use the tetrahedral model.
- The raised 3 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- sp² carbon
- Read sp² as s-p-two.
- One s orbital and two p orbitals mix.
- They form three equivalent sp² hybrid orbitals.
- The three directions use the trigonal-planar model.
- One unhybridised p orbital remains.
- It helps form the pi part of a carbon-carbon double bond.
- The raised 2 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- K
- Read K as kelvin.
- Kelvin is the temperature unit printed on this measurement card.
- 374 K is a temperature.
- K is not a chemical element in this data card.
- kPa and atm
- Read kPa as kilopascal, a pressure unit.
- Read atm as atmosphere, another pressure unit.
- 101.325 kPa equals 1 atm for the normal-boiling condition used here.
- Pressure is a condition attached to the boiling measurement.
- No pressure conversion is required in this Concept.
- normal boiling point
- the boiling temperature measured when the pressure is 101.325 kPa, which is 1 atm
- A measured value keeps its temperature unit, pressure condition and uncertainty if reported.
- ± reported uncertainty
- the stated uncertainty attached to a measured value
- 374 ± 2 K reports central value 374 K and stated uncertainty 2 K
- Keep the reported uncertainty with its value
- no uncertainty calculation is required in this Concept.
- compiled measurement
- a value gathered from a previously reported measurement rather than produced in one classroom experiment
- It remains measured or supplied evidence
- it is not calculated from the molecular drawing.
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
Foundation 1
Two ledgers, two jobs
- Bond-order count completes valency
- neighbouring-atom direction count prepares the accepted geometry model.
Do
For the selected carbon, write both ledgers without copying one number into the other.
Foundation 2
Derive the shape before reading its label
- Four bond directions use the tetrahedral model.
- Three bond directions use the trigonal-planar model.
- The four-direction label is sp³.
- The three-direction label is sp².
- The raised digit counts p orbitals in this model.
Do
- Count directions.
- Name the shape.
- Then say s-p-three or s-p-two.
- State what the raised digit counts.
Foundation 3
Read the measurement card
- 374 K is the central reported temperature.
- ± 2 K is its stated uncertainty.
- K is the kelvin temperature unit.
- 101.325 kPa, or 1 atm, is the stated pressure condition.
- Compiled means the values came from previously reported measurements.
Do
- Keep the value and K together.
- Keep any reported uncertainty.
- Keep the pressure condition.
- Do not calculate an uncertainty here.
Entry check 1
In CH3-CH2-Cl, identify the Cl-bearing carbon, restore its two H atoms, name each representation fact being used and state what the molecular formula can and cannot prove.
Show the recovery
- The terminal CH2 carbon is bonded to C, Cl, H and H
- expanded, condensed and skeletal readings must preserve adjacency and bond order, while a molecular formula gives inventory only.
Return to Concepts 1.1-1.2 for one-bond tracing, representations, valence completion, formula and connectivity conservation.
Entry check 2
In CH2=CH-Cl, state the bond-order total at the Cl-bearing carbon.
Show the recovery
2 for C=C plus 1 for C-Cl plus 1 for C-H gives four.
Return to Concept 1.2 and rebuild the bond-order ledger.
Entry check 3
In the displayed chlorobenzene structure, classify the Cl-bearing carbon using the exact Concept 1.5 setting.
Show the recovery
The Cl-bearing carbon is a member of the benzene ring, so its C-Cl setting is aryl.
Return to Concept 1.5 and test ring membership at the carbon directly bonded to Cl.
Entry check 4
In CH2=CH-CH2-Cl, classify the Cl-bearing carbon using the exact Concept 1.5 setting.
Show the recovery
The Cl-bearing carbon is saturated and one C-C bond outside C=C, so its C-Cl setting is allylic.
Return to Concept 1.5 and count the carbon-carbon distance from the Cl-bearing carbon to C=C.
1 · ObjectiveOpen
What you will understand
Apply the accepted HSC geometry model, bond polarity and intermolecular attractions to explain property evidence.
Problems this Concept unlocks
- turn local bond counts into an accepted three-dimensional label
- mark which end of a shared-electron bond has slightly more electron density
- separate bonds inside one molecule from attractions between molecules
- explain supplied boiling and water-mixing evidence with explicit limits
2 · MysteryOpen
The problem to explain
Read these words and symbols first
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
- K
- Read K as kelvin.
- Kelvin is the temperature unit printed on this measurement card.
- 374 K is a temperature.
- K is not a chemical element in this data card.
- kPa and atm
- Read kPa as kilopascal, a pressure unit.
- Read atm as atmosphere, another pressure unit.
- 101.325 kPa equals 1 atm for the normal-boiling condition used here.
- Pressure is a condition attached to the boiling measurement.
- No pressure conversion is required in this Concept.
- normal boiling point
- the boiling temperature measured when the pressure is 101.325 kPa, which is 1 atm
- A measured value keeps its temperature unit, pressure condition and uncertainty if reported.
- ± reported uncertainty
- the stated uncertainty attached to a measured value
- 374 ± 2 K reports central value 374 K and stated uncertainty 2 K
- Keep the reported uncertainty with its value
- no uncertainty calculation is required in this Concept.
- compiled measurement
- a value gathered from a previously reported measurement rather than produced in one classroom experiment
- It remains measured or supplied evidence
- it is not calculated from the molecular drawing.
- Three supplied structures have formula C4H9Br.
- Their compiled normal boiling points are 374 ± 2 K, 364.3 ± 0.9 K and 346.4 K.
- Place the measurements in increasing order.
- State what remains the same.
- State what changes.
Your decision
- Sort the supplied values.
- Keep each uncertainty with its central value.
- Compare atom inventory and connectivity.
- Do not invent a cause yet.
3 · InvestigationOpen
Investigation
Investigation 1
Count directions before naming geometry
Read these words and symbols first
- bond direction
- one directly bonded atom seen from the selected carbon
- A double-bonded atom is one neighbour direction, although the bond-order total includes two.
Do
Write two ledgers: direction count and bond-order total.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 2
Apply the accepted local geometry model
Read these words and symbols first
- bond direction
- one directly bonded atom seen from the selected carbon
- A double-bonded atom is one neighbour direction, although the bond-order total includes two.
- sp³ carbon
- Read sp³ as s-p-three.
- One s orbital and three p orbitals mix.
- They form four equivalent sp³ hybrid orbitals.
- The four directions use the tetrahedral model.
- The raised 3 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- sp² carbon
- Read sp² as s-p-two.
- One s orbital and two p orbitals mix.
- They form three equivalent sp² hybrid orbitals.
- The three directions use the trigonal-planar model.
- One unhybridised p orbital remains.
- It helps form the pi part of a carbon-carbon double bond.
- The raised 2 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- tetrahedral
- Four bond directions point towards four corners around one carbon in the accepted three-dimensional model.
- About 109.5 degrees is an idealised model angle, not an exact value for every molecule.
- trigonal planar
- Three bond directions lie around one carbon in one plane in the accepted model.
- About 120 degrees is an idealised model angle.
Do
Derive the count first, then attach the model label to that carbon only.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 3
Keep direction count separate from bond-order count
Read these words and symbols first
- bond direction
- one directly bonded atom seen from the selected carbon
- A double-bonded atom is one neighbour direction, although the bond-order total includes two.
Do
Write the neighbour list and bond-order sum on separate lines.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 4
Reject whole-molecule shortcuts
Read these words and symbols first
- sp² carbon
- Read sp² as s-p-two.
- One s orbital and two p orbitals mix.
- They form three equivalent sp² hybrid orbitals.
- The three directions use the trigonal-planar model.
- One unhybridised p orbital remains.
- It helps form the pi part of a carbon-carbon double bond.
- The raised 2 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- sp³ carbon
- Read sp³ as s-p-three.
- One s orbital and three p orbitals mix.
- They form four equivalent sp³ hybrid orbitals.
- The four directions use the tetrahedral model.
- The raised 3 counts the p orbitals used in this model.
- It is not an atom count, charge, valency or exponent.
- The label belongs to one selected carbon.
- tetrahedral
- Four bond directions point towards four corners around one carbon in the accepted three-dimensional model.
- About 109.5 degrees is an idealised model angle, not an exact value for every molecule.
- trigonal planar
- Three bond directions lie around one carbon in one plane in the accepted model.
- About 120 degrees is an idealised model angle.
- bond direction
- one directly bonded atom seen from the selected carbon
- A double-bonded atom is one neighbour direction, although the bond-order total includes two.
Do
Classify each selected carbon independently.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 5
Compare pull on the shared pair
Read these words and symbols first
- shared electron pair
- A covalent bond contains electrons shared by two bonded atoms.
- An electron pair means two electrons considered together.
- The C-Br single bond contains one shared pair in this school model.
- Sharing need not be equal.
- The electrons remain inside the bond rather than becoming free ions.
- electronegativity
- an atom's tendency to pull a shared bonding pair towards itself
- Compare values on the same declared scale.
- The Pauling numbers 2.55 and 2.96 are relative scale values.
- They have no physical unit.
Do
Compare carbon and X values on the same scale.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 6
Derive C-X partial charges
Read these words and symbols first
- shared electron pair
- A covalent bond contains electrons shared by two bonded atoms.
- An electron pair means two electrons considered together.
- The C-Br single bond contains one shared pair in this school model.
- Sharing need not be equal.
- The electrons remain inside the bond rather than becoming free ions.
- electronegativity
- an atom's tendency to pull a shared bonding pair towards itself
- Compare values on the same declared scale.
- The Pauling numbers 2.55 and 2.96 are relative scale values.
- They have no physical unit.
- δ+ and δ−
- Read δ+ as delta plus.
- Read δ− as delta minus.
- δ is the Greek letter delta.
- The signs mark slightly positive and slightly negative ends caused by unequal electron density.
- Delta means partial.
- Cδ+ and Brδ− are not free C+ and Br− ions.
- polar covalent bond
- a shared-electron bond with unequal electron density
- One polar bond alone does not establish whole-molecule charge separation, water solubility or boiling point.
Do
State direction first, then partial charges, then say not ions.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 7
Ask what boiling separates
Read these words and symbols first
- intramolecular
- inside one molecule
- The covalent C-X bond is intramolecular.
- intermolecular
- between separate molecules
- Boiling mainly overcomes intermolecular attractions, not C-X bonds.
Do
Name the particles before and after boiling.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 8
Build the electron-cloud picture
Read these words and symbols first
- electron cloud
- the spread-out region around atoms where a molecule's electrons are found
- The word cloud describes a probability region, not a solid material shell.
Do
- Point to the first changing distribution and then the neighbouring response
- do not invent ions.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 9
Build the dispersion model
Read these words and symbols first
- electron cloud
- the spread-out region around atoms where a molecule's electrons are found
- The word cloud describes a probability region, not a solid material shell.
- London dispersion
- attraction that begins when one momentarily uneven electron distribution makes a neighbouring distribution uneven
- Every molecule has it
- no permanent ions are created.
- polarizability
- how easily an electron cloud is distorted
- Use it only inside a controlled comparison.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
Do
State the controlled variable before predicting.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 10
Read a boiling card lawfully
Read these words and symbols first
- K
- Read K as kelvin.
- Kelvin is the temperature unit printed on this measurement card.
- 374 K is a temperature.
- K is not a chemical element in this data card.
- kPa and atm
- Read kPa as kilopascal, a pressure unit.
- Read atm as atmosphere, another pressure unit.
- 101.325 kPa equals 1 atm for the normal-boiling condition used here.
- Pressure is a condition attached to the boiling measurement.
- No pressure conversion is required in this Concept.
- normal boiling point
- the boiling temperature measured when the pressure is 101.325 kPa, which is 1 atm
- A measured value keeps its temperature unit, pressure condition and uncertainty if reported.
- ± reported uncertainty
- the stated uncertainty attached to a measured value
- 374 ± 2 K reports central value 374 K and stated uncertainty 2 K
- Keep the reported uncertainty with its value
- no uncertainty calculation is required in this Concept.
- compiled measurement
- a value gathered from a previously reported measurement rather than produced in one classroom experiment
- It remains measured or supplied evidence
- it is not calculated from the molecular drawing.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
Do
- Keep the value and K together.
- Keep every reported uncertainty.
- Keep the 101.325 kPa normal-boiling condition.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 11
Give effective contact one precise job
Read these words and symbols first
- electron cloud
- the spread-out region around atoms where a molecule's electrons are found
- The word cloud describes a probability region, not a solid material shell.
- compactness
- a qualitative description of how bunched together the carbon skeleton and electron cloud appear in the supplied same-formula set
- It is not a measured area or a number.
- Use it only for the supplied comparable structures.
- effective contact
- in the school model, how much of two neighbouring molecular electron clouds can approach closely across their shapes
- It is not a literal flat surface area, does not supply a number and is used only for the supplied comparable C4H9Br set.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
Do
Compare only the three supplied shapes and do not turn the model into a measured area.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 12
Bound the branching conclusion
Read these words and symbols first
- normal boiling point
- the boiling temperature measured when the pressure is 101.325 kPa, which is 1 atm
- A measured value keeps its temperature unit, pressure condition and uncertainty if reported.
- compactness
- a qualitative description of how bunched together the carbon skeleton and electron cloud appear in the supplied same-formula set
- It is not a measured area or a number.
- Use it only for the supplied comparable structures.
- effective contact
- in the school model, how much of two neighbouring molecular electron clouds can approach closely across their shapes
- It is not a literal flat surface area, does not supply a number and is used only for the supplied comparable C4H9Br set.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
Do
State same formula, measured order and the three-item limit.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 13
Use an attraction ledger for water
Read these words and symbols first
- solubility
- the amount of a substance that can mix uniformly with a solvent under stated conditions
- Polar bond does not mean water-miscible.
- intermolecular
- between separate molecules
- Boiling mainly overcomes intermolecular attractions, not C-X bonds.
- polar covalent bond
- a shared-electron bond with unequal electron density
- One polar bond alone does not establish whole-molecule charge separation, water solubility or boiling point.
- water-attraction ledger
- Water has a slightly negative oxygen end and slightly positive hydrogen ends.
- Water molecules attract one another strongly.
- A haloalkane can attract water through its polar C-X bond.
- Its hydrocarbon part gives weaker attraction to water.
- Mixing is favourable only if the new water-haloalkane attractions compensate enough for attractions disrupted during mixing.
- This is a qualitative HSC explanation.
- It does not calculate an exact solubility.
Do
- List disrupted attractions.
- List formed attractions.
- State the bounded observation.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 14
Label every claim by evidence job
Read these words and symbols first
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
Do
Attach one evidence-status label and one limitation to each conclusion.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Investigation 15
Run the complete property algorithm
Read these words and symbols first
- evidence status
- whether a statement is graph-derived, accepted-model, predicted, observed or measured
- Do not relabel a measured value as calculated from structure.
- controlled comparison
- a comparison that states what is held constant and what changes
- A trend from one controlled set is not automatically universal.
Do
Stop if any required evidence is missing.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
4 · MeaningOpen
Build the meaning
Meaning 1
Count directions before naming geometry
- At one selected carbon, list directly bonded atoms.
- Count a double-bonded atom once as a direction.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 2
Apply the accepted local geometry model
- Four saturated directions map to tetrahedral sp3
- three directions at C=C or benzene map to trigonal-planar sp2.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 3
Keep direction count separate from bond-order count
At the selected carbon, the C=C partner is one neighbouring atom and therefore one direction, while that same double bond contributes two bond-order units.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 4
Reject whole-molecule shortcuts
- One molecule can contain sp2 and sp3 carbons
- a flat drawing does not make an sp3 carbon planar
- a C=C partner remains one neighbouring-atom direction.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 5
Compare pull on the shared pair
Electronegativity compares how strongly bonded atoms pull a shared electron pair.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 6
Derive C-X partial charges
For the supplied neutral C-Br bond, Br pulls more strongly: electron density shifts towards Br, giving Cδ+—Brδ−.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 7
Ask what boiling separates
- C-X is inside a molecule.
- Boiling separates intact molecules by overcoming attractions between molecules.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 8
Build the electron-cloud picture
- An electron cloud is the spread-out region where a molecule's electrons are found.
- Its distribution can become briefly uneven, and that unevenness can make a neighbouring cloud uneven.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 9
Build the dispersion model
- A momentarily uneven electron cloud can make a neighbouring cloud uneven, producing London attraction
- a more polarizable cloud often strengthens it in a controlled family.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 10
Read a boiling card lawfully
- Sort the supplied normal-boiling measurements.
- Use the matching attraction model only after sorting.
- Never calculate those temperatures from the drawing.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 11
Give effective contact one precise job
Within the supplied same-formula C4H9Br set, a less compact shape lets neighbouring electron clouds approach over more of their shapes in the school model.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 12
Bound the branching conclusion
For the supplied C4H9Br set, greater compactness accompanies lower normal boiling point through the school effective-contact model.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 13
Use an attraction ledger for water
- Mixing disrupts water-water and haloalkane-haloalkane attractions and forms water-haloalkane attractions.
- The new attractions may not compensate enough.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 14
Label every claim by evidence job
- A graph gives connectivity
- an accepted model gives geometry
- a trend is a prediction
- a supplied value is measured
- an observation stays qualitative.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
Meaning 15
Run the complete property algorithm
Read graph → classify local geometry → derive bond polarity → identify the physical event → choose controlled evidence → conclude with a limit.
Check
Verify the stated claim with the displayed atom graph, supplied evidence record or explicit accepted-model boundary before continuing.
5 · ExamplesOpen
Worked examples
Example 1 of 6
Four directions versus three
Classify the selected carbons in chloroethane and chloroethene.
Key evidence
- exact neighbours
- bond-order total four
- accepted model
One lawful move at a time
One move at a time
Step 1 of 3
- Action
- List A
- Why
- C, Cl, H, H are four atoms
- Result
- four directions
Answer
The two selected carbons have different local models.
Independent check
- Recount atom neighbours independently
- both carbons still have bond-order total four.
Counter-pattern
Two drawn lines in C=C do not mean two neighbouring carbon atoms.
6 · QuestionsOpen
Questions
Question 1 of 12
Separate direction count from bond-order count before applying a geometry label.
At the chlorine-bearing carbon in structure A, how many neighbouring-atom directions are present before any geometry label is used?
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