C=md/ms*100=>md=C*ms/100=10*630/100=63g HNO3
K2CO3 + 2HNO3 = KNO3↓ + CO2↑ + H2O
MHNO3=AH+AN+3AO=1+14+3*16=63g/mol
MKNO3=AK+AN+3AO=39+14+3*16=101g/mol
2*63g HNO3.........................101g KNO3
63g HNO3................................xg
x=101*63/2*63 = Calculeaza !!