200 ml of a 0.500 m ca(no3)2 solution was made, but only 150 ml of solution are needed. if you pour out 50 ml of the soultion, what is the concentration, in m, of the 150 ml of solution you have left.

Wouldn't it be 100? 150 - 50 would equal 100. Unless I'm not seeing something.

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).