4. ninety-two percent of the atoms of an element have a mass of 28 u, 5% have a mass of 29 u, and the remaining atoms have a mass of 30 u. calculate the average atomic mass and identify
the element.

.92(28)+0.05(29)+0.03(30)=25.76+1.45+0.9=28.11

silicon

Explanation:

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.

it would be b. 6co2 + 6h2o --> c6h12o6 + 6o2