Classify the following as ‘chiral’ and ‘achiral’. (a) Scissors (b) Shoe (c) Hammer (d) Nail (e) Screw (f) T-shirt (g) Foot (h) Fork (i) Nose
The Correct Answer and Explanation is:
To classify the following objects as chiral or achiral, we first need to understand the definitions of these terms:
- Chiral: A molecule or object is considered chiral if it cannot be superimposed on its mirror image, much like how your left and right hands are mirror images but cannot be perfectly aligned on top of one another.
- Achiral: An object or molecule is achiral if it is superimposable on its mirror image. In other words, it can be placed on top of its mirror image with no differences.
Let’s classify the items based on these definitions:
(a) Scissors: Achiral
Scissors are typically symmetrical and can be superimposed on their mirror image. Both handles are identical, making the whole object achiral.
(b) Shoe: Achiral
A shoe, while having a left and right version, has symmetry in its overall shape. The shape itself is achiral, even though it is different when considering a pair of shoes, but it’s more a case of being asymmetric in a practical sense, not because the shoe itself is inherently non-superimposable on its mirror image.
(c) Hammer: Achiral
A hammer has a handle and a head, both of which are symmetrical along their axes. No matter how you orient it, it can be superimposed on its mirror image.
(d) Nail: Achiral
A nail, being a simple rod-shaped object, is symmetrical and can be superimposed on its mirror image. Hence, it is achiral.
(e) Screw: Chiral
A screw has a helical thread which makes it chiral. It cannot be superimposed on its mirror image because of the twist in its structure.
(f) T-shirt: Achiral
A T-shirt, when viewed from a symmetrical perspective (like front to back), is achiral. The T-shirt’s shape doesn’t prevent it from being superimposed on its mirror image.
(g) Foot: Chiral
A human foot is chiral because the left and right feet are mirror images but cannot be superimposed on each other. This is due to the asymmetry in the arches and toes.
(h) Fork: Achiral
A fork has symmetry along its axis, making it achiral. Its design is such that it can be superimposed on its mirror image.
(i) Nose: Achiral
A nose is generally considered achiral from a symmetry perspective. Despite some minor asymmetry (in some people), it can be argued that a nose is more or less superimposable on its mirror image when considering the overall structure.
In conclusion:
- Chiral: Screw, Foot
- Achiral: Scissors, Shoe, Hammer, Nail, T-shirt, Fork, Nose
Explanation:
An object is chiral if it has “handedness,” meaning it has two non-superimposable mirror images (left and right). This property is typically seen in objects with complex or asymmetric structures (like the screw or the foot). Achiral objects, on the other hand, are symmetric or have a design that allows them to be superimposed on their mirror image (like a T-shirt, hammer, or nail).
