The one that is NOT suitable for the removal of permanent hardness of water is :

For a reaction X + Y ⇌ 2Z , 1.0 mol of X, 1.5 mol
of Y and 0.5 mol of Z were taken in a 1 L vessel and
allowed to react. At equilibrium, the concentration
of Z was 1.0 mol L^–1. The equilibrium constant of reaction
is $${x \over {15}}$$. The value of x is _________.

The volume, in mL, of 0.02 M K₂Cr₂O₇ solution required to react with 0.288 g of ferrous oxalate in acidic medium is _______.
(Molar mass of Fe = 56 g mol^–1)

Considering that $$\Delta $$₀ > P, the magnetic moment
(in BM) of [Ru(H₂O)₆]²⁺ would be _________.