Can someone help me please

Strange question. All the answers are D

Explanation:

I don't exactly know how you should answer this. I can find the charge on Chromium. The only hope is that they are all the same.

[Cr(OH)_-6]^-3

x - 6 = -3   Add 6

x = -3 + 6

x = 3

CrO4 ^-2

x - 4*2 = - 2   add 8

x = -2 + 8

x = 6

Water has no effect on the charge. The chromium has a charge of +2

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.