Final answer:
Lithium, sodium, and potassium appear shiny and silvery when cut, but quickly tarnish when exposed to air due to the formation of oxide layers on the surface.
Step-by-step explanation:
Lithium, sodium, and potassium all have similar appearances when cut - they are shiny metals.
When these metals are fresh, their surface is silvery and very reflective. However, upon exposure to air, they quickly react with oxygen to form oxides, tarnishing their appearance.
For example, if you were to cut a piece of fresh lithium, sodium, or potassium, it would appear shiny and silvery. But if you were to leave it exposed to air for some time, you would observe the formation of a dull colored oxide layer on the surface.