1．
\(\rm{900 ℃}\)时，向\(\rm{2.0 L}\)恒容密闭容器中充入\(\rm{0.40 mol}\)乙苯，发生反应：
\(\rm{+H_{2}(g)}\) \(\rm{ΔH=a kJ·mol^{-1}}\)。经一段时间后达到平衡。反应过程中测定的部分数据见下表：
时间\(\rm{/min}\) | \(\rm{0}\) | \(\rm{10}\) | \(\rm{20}\) | \(\rm{30}\) | \(\rm{40}\) |
\(\rm{n(}\)乙苯\(\rm{)/mol}\) | \(\rm{0.40}\) | \(\rm{0.30}\) | \(\rm{0.24}\) | \(\rm{n_{2}}\) | \(\rm{n_{3}}\) |
\(\rm{n(}\)苯乙烯\(\rm{)/mol}\) | \(\rm{0.00}\) | \(\rm{0.10}\) | \(\rm{n_{1}}\) | \(\rm{0.20}\) | \(\rm{0.20}\) |
下列说法正确的是\(\rm{(}\) \(\rm{)}\)