3.(2021河南,9)黑火药爆炸时的反应为 +2KN(O)_(3)+-|||-xlongequal (点燃)X+(N)_(2)uparrow +3C(O)_(2)uparrow 则X是 ()-|||-A.K2S B.K2SO3 C.K2SO4 D.K2S2O3