Which of these metals is the least reactive?
in
caldum
sodium
potassium

Calcium

Explanation:

It is because sodium and potassium are highly reactive metal i.e. Group 1 but calcium is Group 2 element. So, calcium is least reactive.

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

where are the choice options?