The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is _________.

$$\mathrm{Ti}^{2+}, \mathrm{Cr}^{2+} \text { and } \mathrm{V}^{2+}$$

The number of moles of methane required to produce $$11 \mathrm{~g} \mathrm{~CO}_2(\mathrm{g})$$ after complete combustion is : (Given molar mass of methane in $$\mathrm{g} \mathrm{~mol}^{-1}: 16$$ )

The quantity of silver deposited when one coulomb charge is passed through $$\mathrm{AgNO}_3$$ solution :

The metal atom present in the complex MABXL (where A, B, X and L are unidentate ligands and $$\mathrm{M}$$ is metal) involves $$\mathrm{sp}^3$$ hybridization. The number of geometrical isomers exhibited by the complex is :