30. 氮氣和氫氣的最初混合物在固定溫度下進行反應：3 H2(g) + N2(g) ⇌ 2 NH3(g) 當到達平衡時 [H2] = 4.0 M、[N2] = 7.0 M 和 [NH3] = 2.0 M。請問氮氣和氫氣的最初濃度分別是多少？ (A) [H2]0 = 3.0 M, [N2]0 = 5.0 M (B) [H2]0 = 7.0 M, [N2]0 = 6.0 M (C) [H2]0 = 7.0 M, [N2]0 = 8.0 M (D) [H2]0 = 11.0 M, [N2]0 = 10.0 M