4 NH3 + 7 02- 4 NO2 + 6H2O The balanced equation above shows that 8.0 moles of NH3 requires mole(s) of O2
O 8.0
0 10.0
0 12.0
0 14.0

D. h2o + h2o > h3o + oh- confirmed.

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.