Consult to find (a) two metals less dense than water, (b) two metals more dense than mercury,(c) the densest known solid metallic element, and (d) the densest known solid nonmetallic element.

(a) lithium and potassium

(b) gold and osmium

(c) Osmium

(d) Iodine

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.

1 mole of water is 18 grams.

Then,

150 grams of water,

→ 1/18 × 150

→ 25/3

→ 8.33333 . . .

Hence, 150 grams of water is 8.3 moles.