A:将5.85gNaCl晶体溶入100mL水中,制得1mol/L的NaCl溶液
B:11.2LHCl气体溶于水配成0.5L溶液,其浓度为1mol/L
C:浓度为2.00 mol/L的盐酸溶液1L,将溶液加热蒸发浓缩至0.5L 其浓度小于4.00mol/L
D:向100mL1mol/LCuSO4溶液加入25g 胆矾晶体,溶液浓度变为2mol/L
如图是电磁继电器的构造和工作电路示意图.要使电磁铁对衔铁的吸引力变大,以下做法可行的是( )
— Does your son ________an hour ________ his homework after school?
— No, shorter than that now, about half an hour.