The molar mass of the water insoluble product formed from the fusion of chromite ore (FeCr₂O₄) with Na₂CO₃ in presence of O₂ is ___________ g mol⁻¹.
Niobium $(\mathrm{Nb})$ and ruthenium $(\mathrm{Ru})$ have " $x$ " and " $y$ " number of electrons in their respective 4 d orbitals. The value of $x+y$ is __________.
A transition metal '$$\mathrm{M}$$' among $$\mathrm{Sc}, \mathrm{Ti}, \mathrm{V}, \mathrm{Cr}, \mathrm{Mn}$$ and $$\mathrm{Fe}$$ has the highest second ionisation enthalpy. The spin-only magnetic moment value of $$\mathrm{M}^{+}$$ ion is _______ BM (Near integer)
(Given atomic number $$\mathrm{Sc}: 21, \mathrm{Ti}: 22, \mathrm{~V}: 23, \mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26$$)
Number of colourless lanthanoid ions among the following is __________.
$$\mathrm{Eu}^{3+}, \mathrm{Lu}^{3+}, \mathrm{Nd}^{3+}, \mathrm{La}^{3+}, \mathrm{Sm}^{3+}$$