Which is an example of a precipitation reaction?
a.
a solution of hcl mixes with a solution of naoh to produce a solution of nacl.
b.
a solution of agno3 mixes with a solution of nacl to produce solid agcl and a solution of nano3.
c.
solid c6h12o6 combines with o2 gas to produce co2 gas and h2o gas.
d.
solid fe combines with o2 gas to produce solid fe2o3.

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.

14 days is the half-life of phosphorus-32