In the periodic table, the most reactive metals are found a. in group 1, the first column on the left. b. in period 1, the first row across the top. c. in groups 13 through 16 in the center. d. in periods 6 and 7 at the bottom.

Group 1, the first column on the left.

The correct answer is Option a.

Explanation:

Chemical reactivity is defined as the property of an element to loose or gain electrons.

Metals are the elements which loose electrons and hence, their chemical reactivity will be the tendency to loose electrons.

Their chemical reactivity decreases as we move from left to right in a period because the valence shell come closer to nucleus as we move from left to right. So, removal of electron in the valence shell becomes difficult due to greater attraction between nucleus and valence electron.

Their chemical reactivity increases as we move from top to down the group because the electron gets added up in the new shell. So, the electron in the outermost orbital gets far away from the nucleus. And hence, the electron will be lost easily.

Hence, the correct answer is Option a.