Answers to Questions

Question 1

The spade has a plane of symmetry running top to bottom, bisecting the handle and the blade and set at 90 to the blade.

A foot is not symmetrical. Try putting your shoes on the wrong feet to check!

A car is not symmetrical (for example left and right hand drive cars are readily distinguished). The body shell of a car will often be symmetrical.

Both cross-head and flat-head screwdrivers are symmetrical. They have a plane of symmetry similar to that found in the spade.

There will be an arrangement in which an all black cat is symmetrical. This is when its legs are evenly spaced, it is looking forward and its tail is in line with its spine. It then has a plane of symmetry running front to back, set at 90 to the floor.

A black cat with one white foot, even in this unlikely arrangement, is not symmetrical.

Corkscrews do not possess a plane, axis or centre of symmetry. Hence it is possible to distinguish between left- and right-handed corkscrews.

Whilst a bicycle frame is symmetrical, the pedals, chain gears and so on make a complete bicycle asymmetrical.

Question 2

Ethanal is not chiral. It has two carbon atoms; one of which has three identical groups (hydrogen atoms) and the other only has three groups attached.

Propan-2-ol is also not chiral, it is symmetrical about the middle carbon atom. Again no carbon atom has four different groups attached to it. Pentan-3-ol is the same.

Pentan-2-ol, however does have a chiral carbon. The second carbon atom of the chain has a CH3 group, an OH group, a hydrogen atom and CH3CH2CH2 group.

Question 3