Answer: Lead will be the least metallic of all the elements given.
Explanation: Metallic character is defined as the tendency of the metals to loose electrons easily.
The metallic character increases down the group and decreases across a period because the size of the elemnt increases down the group and decreases across a period.
Lead belong to Group 14 and Period 6 of the periodic table.
Mercury belongs to Group 12 and Period 6 of the periodic table.
Americium belongs to Group 8 and Period 7 of the periodic table.
Francium belongs to Group 1 and Period 7 of the periodic table.
Order of metallic character:
Francium > Americium > Mercury > Lead
From the order above, the lead will have the least metallic character.