Answer:
(a) lithium and potassium
(b) gold and osmium
(c) Osmium
(d) Iodine
Step-by-step explanation:
(a) Metals generally have high density and high tensile strength. But the metals which have density even less than water are lithium and potassium.
The density of water = 1 g/cm³
Density of lithium = 0.53 g/cm³
Density of potassium = 0.59 g/cm³
(b) The two metals which are more denser than mercury are gold and osmium.
The density of mercury = 13.53 g/cm³
Density of gold = 19.3 g/cm³
Density of osmium = 22.59 g/cm³
(c) The value of density of osmium corresponds the maximum value of the density in the metals. Hence, osmium is the densest known solid metallic element.
(d) The value of density of iodine (4.94 g/cm³) corresponds the maximum value of the density in the non metals. Hence, iodine is the densest known solid non metallic element.