Question

why are sodium (na) and potassium (k) in the same group on the periodic table? (1 point)
they have similar atomic weights.
they are both hard and brittle.
they have similar reactivity.
they are both colorless.

Explanation:

Elements in the same group of the periodic table have similar chemical properties, which are related to their reactivity. Sodium and potassium are both alkali metals (Group 1). Their similar reactivity is due to having one valence electron, which they readily lose in chemical reactions. Atomic weights (molar masses) are not the basis for group placement. Sodium and potassium are soft (not hard) metals. Also, their color (sodium is a silvery - white metal, potassium is also silvery - white when freshly cut but oxidizes quickly) is not a key factor for group classification.

Answer:

They have similar reactivity.