What Are Structural Isomers

The video tutorial covers the concept of alkanes and structural isomers, starting with the first four alkanes: methane, ethane, propane, and butane. It explains how structural isomers have the same molecular formula but different structural arrangements, using butane as an example. The tutorial also discusses the history of lead-free petrol and the role of octane isomers in improving engine performance. Finally, it explores the structural isomers of hexane, providing their formal names and emphasizing the importance of the longest carbon chain in naming isomers.

What is the structural isomer of butane with a three-carbon chain called?

• 3-ethyl butane

• 2-ethyl propane

• 3-methyl butane

• 2-methyl propane

What is the longest carbon chain in the structural isomer of octane discussed in the video?

• Four carbon atoms

• Five carbon atoms

• Six carbon atoms

• Seven carbon atoms

What was the main reason for using lead in petrol historically?

• To decrease fuel cost

• To improve engine power

• To reduce engine knocking

• To increase fuel efficiency

What is the environmental impact of lead from car exhausts?

• It reduces global warming

• It is harmless to the environment

• It improves air quality

• It is toxic and has spread globally

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

• 3-methyl hexane

• 2-ethyl butane

• 2-methyl pentane

• 2,3-dimethyl butane

How many structural isomers of hexane are based on butane?

• Two

• Four

• One

• Three

What is the basis for naming structural isomers?

• The number of hydrogen atoms

• The number of double bonds

• The length of the longest carbon chain

• The total molecular weight