In each of the following, how many moles of each element or compound are present? 10.0 g h = 0.25 g na = 1.0 x 102 mg h2o =

Moles =  mass /molar   mass
  moles  of H   =  10g/1g/mol  (molar mass of  H)  =  10  moles of  H

moles  of Na  = 0.25g  / 23  g/mol (molar   mass  of  Na)  =  0.0109  moles of  Na

moles  of  H20  = mass of  water  /molar  mass  of  water( 18 g/mol)
mass  of  water  in  g  =  1  g   =  1000mg  what  about  1  x10^2  mg  =?g
100mg  x1g/1000mg=0.1 g
moles  is therefore=  0.1g/  18 g/mol= 5.556  x10^-3moles  of H20

What are the options? i can you if you give them.

The answers is a nuclear changes