The hardness of a water sample containing 10^–3 M MgSO₄ expressed as CaCO₃ equivalents (in ppm) is ______.
(molar mass of MgSO₄ is 120.37 g/mol)

The de Broglie wavelength of an electron in the 4th Bohr orbit is :

The major product (Y) in the following reactions is :

Complex X of composition Cr(H₂O)₆Cl_n has a spin only magnetic moment of 3.83 BM. It reacts with AgNO₃ and shows geometrical isomerism. The IUPAC nomenclature of X is :