Ionising radiation is emitted all the time by sources. what one word completes the sentence?

Radioactive substances give out radiation all of the time. There are three types of nuclear radiation: alpha, beta and gamma. Alpha is the least penetrating, while gamma is the most penetrating. Nonetheless, all three are ionising radiation: they can knock electrons out of atoms and form charged particles.

The balanced chemical reaction for the combustion of carbon is,
                                C + O2 ---> CO2
6 grams of carbon is equal to 0.5 mols of carbon. This also corresponds to 0.5 mols of carbon dioxide. Using the ideal gas law through STP,
                                V = nRT / P
where R is the universal gas constant, 0.0821 L.atm /mol K, T is 273 K and P is 1 atm. Substituting the known values to the equation,
      V = (0.5 mols)(0.0821 L.atm/mol K)(273 K) / 1 atm = 11.2 L
Thus, the answer to the question is letter B.