How many moles are there in 1.09 kg of al(oh)3? how many formula units are there in 2.55 g of pb(co3)2?

  question   1
moles  =  mass/molar  mass  of  Al(OH)3
convert   Kg  to  g
that  is  1.09  x  1000=1090g

moles  is  therefore=1090g/78(molar  mass  of Al(OH)3)=  13.974 moles

   question  2
moles=2.55g/327.2(molar   mass  of  Pb(CO3)2=  7.79  x   10^-3   moles
from  avogadro  constant
1moles=6.02  x10^23  formula  units
what  about  7.79  x  10  ^-3
={(7.79  x  10^-3)moles  x ( 6.02  x10^23)} /1  mole=4.69  x10^21  formula  units

D. is the answer hope that you