Answer:
Rb > Ca > C
Step-by-step explanation:
The order of decreasing atomic radius of the elements given is Rb > Ca > C.
Atomic radius of a substance is the half of the internuclear distance between two covalently bonded atoms of non-metallic elements or half of the distance between two nuclei in the solid state of metals.
- Across a period, the atomic radius decreases from left to right on the periodic table.
- Also, it increases from top to bottom.
Therefore, Rubidium from the choices has the greatest atomic radius and Carbon has the lowest.