This mystery element has a reputation for being tough. That's

because when combined with other elements, it forms strong,

durable compounds. Some are nearly as hard as diamonds-the

hardest material on Earth. But in its pure form, the grayish-

white transition metal is soft enough to cut with a saw. Most

of the mystery element- about 75 percent-comes from

China. There are also large deposits in Canada, Russia, and the

U. S.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

1 a

2 d

3 a

4 c

explanation:

tracks, burrows, eggshells, nests, tooth marks, or gastroliths