6. 5g oxides of lead heated and it was reduced to 4. 2g of lead metals. Calculate the empirical formulae of the oxides

just to simplify the math assume 6500g oxides...

moles of lead=4200/207=20.2 moles=20
Moles of Ox=2300/16=143.7=140 notice the original data was to TWO significant digits..

ratio of O to Pb=140/20 =7

Pb1O7