Amongst the following, the form of water with the lowest ionic conductance at is :
Hydrogen has three isotopes (A),(B), and (C). If the number of neutron(s) in (A), (B) and (C) respectively, are (x), (y) and (z), the sum of (x),(y) and (z) is :
The one that is NOT suitable for the removal of the permanent hardness of water is: