Total number of species from the following which can undergo disproportionation reaction is ________.

$$\mathrm{H}_2 \mathrm{O}_2, \mathrm{ClO}_3^{-}, \mathrm{P}_4, \mathrm{Cl}_2, \mathrm{Ag}, \mathrm{Cu}^{+1}, \mathrm{~F}_2, \mathrm{NO}_2, \mathrm{K}^{+}$$

Number of geometrical isomers possible for the given structure is/are _________.

The $$\mathrm{pH}$$ of an aqueous solution containing $$1 \mathrm{M}$$ benzoic acid $$\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$$ and $$1 \mathrm{M}$$ sodium benzoate is 4.5. The volume of benzoic acid solution in $$300 \mathrm{~mL}$$ of this buffer solution is _________ $$\mathrm{mL}$$. (given : $$\log 2=0.3$$)

$$\mathrm{NO}_2$$ required for a reaction is produced by decomposition of $$\mathrm{N}_2 \mathrm{O}_5$$ in $$\mathrm{CCl}_4$$ as by equation

$$2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightarrow 4 \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$$

The initial concentration of $$\mathrm{N}_2 \mathrm{O}_5$$ is $$3 \mathrm{~mol} \mathrm{~L}^{-1}$$ and it is $$2.75 \mathrm{~mol} \mathrm{~L}^{-1}$$ after 30 minutes.

The rate of formation of $$\mathrm{NO}_2$$ is $$\mathrm{x} \times 10^{-3} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~min}^{-1}$$, value of $$\mathrm{x}$$ is _________. (nearest integer)