钢铁是使用最多的金属材料．如图实验装置是模拟炼铁的实验．其中A是实验室用草酸（H₂C₂O₄）和浓硫酸加热分解产生CO．E是利用得到一氧化碳还原氧化铁得到铁．（提示：浓硫酸具有吸水性；草酸分解化学方程式：H₂C₂O₄  H₂O+CO₂↑+CO↑）

请回答下列问题：

铁与稀盐酸(HCl)反应生成氢气和氯化亚铁(FeCl₂)。将7克铁粉与足量的盐酸反应，产生的氢气在标准状况下的体积是多少升？（在标准状况下，氢气的密度为0.0899g/L，计算结果精确到0.01）

    Today is Sunday. We don't go to school. So after breakfast I go to the park with some of my good friends. In the park, there are many people. They are doing exercise. Some women are dancing. Some people are playing badminton. Some girls are skipping, and some people are walking and running. Why do they work so hard? Because they want to be strong and healthy.

如图，⊙O的外切正六边形ABCDEF的边长为2，则图中阴影部分的面积为____ ．

某地有一个大型的石灰厂，其白色的粉尘使周围的植物都变成了灰白色．如果该厂长期生产，请你推测，该厂周围环境中不同颜色的蛾类最可能的变化结果是下图中的（　　）