题目

                    Would you be our volunteers? Are you ready to join psychological(心理的) experiment from the department of psychology as a volunteer next two weeks from Dec. 2 to Dec. 15? We are going to do a psychological experiment on sound recognition（识别）. Warmly welcome to join us and you will be paid 30 yuan after one-hour experiment. Experiment time:  8:00-11:30 on Tuesday and Thursday.                 10:00-21:00 on Wednesday.                 18:00-21:00 on Sunday, Monday, Tuesday                 8:0把2.5mol A和2.5mol B混合盛入2L容积的密闭容器里发生反应3A（g）+B（g）?x C（g）+2D（g），经5s后反应达平衡．在此5s内C的平均反应速率为0.2mol?L-1?s-1，同时生成1mol D．试求：（1）试算x的值；（2）达平衡时B的转化率；（3）若达平衡时，该反应放出Q kJ的热量，写出该反应的热化学方程式；（4）若温度和压强维持不变，达平衡时容器内气体的体积是多少？