Understanding Structural Isomers

What are structural isomers?

• Compounds with different molecular and structural formulas

• Compounds with the same molecular formula but different structural formulas

• Compounds with different molecular formulas but the same structural formula

• Compounds with the same molecular and structural formulas

Which of the following is the molecular formula for butane?

• C5H12

• C3H8

• C4H10

• C6H14

What is the name of the isomer of butane with a three-carbon chain and a methyl group?

• 2-methylpropane

• 3-ethylbutane

• 2-ethylpropane

• 3-methylbutane

Why was lead added to petrol in the past?

• To reduce engine knocking

• To improve fuel economy

• To increase the octane number

• To decrease emissions

What is the main component of petrol used in cars?

• Ethane

• Octane

• Methane

• Propane

Which isomer of octane has a five-carbon chain with an ethyl and a methyl group?

• 3-ethyl-3-methylpentane

• 3,3-dimethylpentane

• 2-ethyl-2-methylpentane

• 2,2-dimethylpentane

How many structural isomers does hexane have?

• Five

• Four

• Three

• Two

Which of the following is a hexane isomer with a four-carbon chain?

• 3-methylpentane

• 2-methylpentane

• 2,2-dimethylpentane

• 2,3-dimethylbutane

What determines the naming of structural isomers?

• The presence of double bonds

• The length of the longest carbon chain and branching

• The number of hydrogen atoms

• The total number of carbon atoms

What is the key characteristic of structural isomers?

• They have different molecular weights

• They have the same structural formula

• They have the same molecular formula but different structures

• They are always liquids at room temperature