-M(miu)= (39gK+35,5gCl+3x16gO)/mol= 122,5g/mol KClO3
-n(niu)= 9,8/122,5KClO3=0,08mol
-din ecuatia reactiei calculez moli O2
2mol......................3mol
2KClO3---> 2KCl +3O2
0,08.........................x=0,12molO2
-Calculez volumul acestor moli
n(niu)= V/Vm---> V,O2= 0,12molx22,4l/mol=...................CALCULEAZA !!!