Răspuns:
Explicație:
a) 1 molec HNO3
1 atom H + 1 at N + 3 at O = 5 atomi
b) 4 molec SO2
4 ( 1 at S + 2 at O) = 4x3= 12 atomi
c) 3 molec Al2(SO4)3
3 [ 2 at Al + 3( 1 at S + 4 at O)] = 3 x (2 + 15) = 51 atomi
d) 7 molec NH3
7 ( 1 at N + 3 at H) = 7x4 = 28 atomi