He thought himself to his friends because his family was rich.

A．higher

B．better

C．richer

D．superior

如图所示，通电5min后，第③极增重2．16g，同时在A池中收集到标准状况下的气体224mL，A池中混合液的体积为200mL（电解前后体积视为不变），求通电前A池中原混合溶液Cu²⁺的浓度。