• # question_answer 84) The volume of water which must be added to a mixture of $350\text{ }c{{m}^{3}}$of $6M\text{ }HCl$and $650\text{ }mL$of $3M\text{ }HCl$to get a resulting solution of 3M concentration is A)  $75\text{ }mL.$           B)  $150\text{ }mL.$C)  $100\text{ }mL.$          D)  $350\text{ }mL.$

${{N}_{3}}{{V}_{3}}={{N}_{1}}{{V}_{1}}+{{N}_{2}}{{V}_{2}}$ $3\times {{V}_{3}}=6\times 350+3\times 650$ ${{V}_{3}}=700+650=1350$ volume of added water $=1350-(350+650)$ $=350\,mL$