a piece of mg is dissolved in 40ml of n/10 hcl completely.the excees of acid was neutralised by 15ml of n/5 naoh.the weight of mg is

The excess of HCl was neutralised by NaOH thus equivalents of HCl=equivalents of NaOHN|10xVolume=N|5x15Thus volume of HCl reacted with NaOH is 30mlThen the volume that might have reacted with Mg should be 10mlNow equivalent of Mg=equivalent of 10ml HClWeight of Mg|Equivalent weight of Mg=NxV (HCl)Equivalent weight of Mg=Molar weight|Valency factor (Valency factor should be 2)Thus weight will come out as 12g!