Tracey has a solid wood block and a solid gold block. She drops each into a tub of water. The wood block floats and the gold block sinks. If the density of the water is 1.0 g/cm3, what does this tell Tracey about the densities of the two blocks? A.
The wood block has a density greater than 1.0 g/cm3 and the gold block has a density lower than 1.0 g/cm3

B.
The wood block has a density lower than 1.0 g/cm3 and the gold block has a density greater than 1.0 g/cm3

C.
Both blocks have a density lower than 1.0 g/cm3

D.
Both blocks have a density greater than 1.0 g/cm3

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.

the maximum mass of nh3 is nh3 in grams