Question

Which list of elements is placed in order from most reactive to least reactive?

A. K, Ca, Kr, Ge
B. K, Ca, Ge, Kr
C. Ca, K, Kr, Ge
D. Ge, Kr, Ca, K

Answer 1

All four elements given in the answer choices are on the same period. The least reactive element should be Kr, since it is a noble gas. By that fact alone, B would be the correct answer.

B is also correct as non-d-block metals increase in reactivity from left to right on along a period. The order of the metals (Ge is often considered a metalloid) conforms with that trend.