Question

which element has the smallest atomic radius?
calcium
potassium
scandium
titanium

Explanation:

Atomic radius decreases across a period from left to right due to increasing nuclear charge pulling electrons closer. Calcium (Ca), potassium (K), scandium (Sc), and titanium (Ti) are in the same period. Potassium is in group 1, calcium in group 2, scandium in group 3 and titanium in group 4. As we move from potassium to titanium across the period, the atomic radius decreases.

Answer:

D. titanium