Number of ambidentate ligands in a representative metal complex $$\left[\mathrm{M}(\mathrm{en})(\mathrm{SCN})_{4}\right]$$ is ___________.

[en = ethylenediamine]

If 5 moles of $$\mathrm{BaCl}_{2}$$ is mixed with 2 moles of $$\mathrm{Na}_{3} \mathrm{PO}_{4}$$, the maximum number of moles of $$\mathrm{Ba}_{3}\left(\mathrm{PO}_{4}\right)_{2}$$ formed is ___________ (Nearest integer)

In ammonium - phosphomolybdate, the oxidation state of Mo is + ___________

Let $$A = \{ x \in R:[x + 3] + [x + 4] \le 3\} ,$$

$$B = \left\{ {x \in R:{3^x}{{\left( {\sum\limits_{r = 1}^\infty {{3 \over {{{10}^r}}}} } \right)}^{x - 3}} < {3^{ - 3x}}} \right\},$$ where [t] denotes greatest integer function. Then,