Which of the following statements are true about $\left[\mathrm{NiCl}_4\right]^{2-}$ ?

(a) The complex has tetrahedral geometry

(b) Co-ordination number of Ni is 2 and oxidation state is +4

(c) The complex is $\mathrm{sp}^3$ hybridised

(d) It is a high spin complex

(e) The complex is paramagnetic

$$ \text { Which formula and its name combination is incorrect? } $$

$$ \text { In the complex ion }\left[\mathrm{Fe}\left(\mathrm{C}_2 \mathrm{O}_4\right)_3\right]^{3-} \text {, the co-ordination number of } \mathrm{Fe} \text { is } $$

On treating 100 mL of 0.1 M aqueous solution of the complex $\mathrm{CrCl}_3 \cdot 6 \mathrm{H}_2 \mathrm{O}$ with excess of $\mathrm{AgNO}_3, 2.86 \mathrm{~g}$ of AgCl was obtained. The complex is