Metalloids are the elements found along the stair-step line that distinguishes metals from non-metals. This line is drawn from between Boron and Aluminum to the border between Polonium and Astatine. The only exception to this is Aluminum, which is classified under "Other Metals". read more
Yes it is number four as both silicon(Si) and polonium(Po) are metalloids. and it looks as though one has 3 metalloids myabe a typo or not. read more