1. 4H3PO4 = 4*3+ 4*1+4*4 = 32 atomi
R: b) x=32
2. 2g H2(1 mol).......6,022*10^23 molecule
x g H2......................1 moleculă
x = 0,332*10^(-23) g H2
3. MNH3 = 17g/mol. %N= 14/17*100 = 82,35
MHNO3 = 63g/mol %N = 14/63*100 = 22,22
MNaNO3 = 85g/mol.. %N = 14/85*100 = 16,47
R: a) NH3
4. R: c) 6,023*10^23
5. MH2O = 18g/mol
18g H2O.............2g H2
x g H2O.............6g H2
x = 54g H2O
R: b