The number of white coloured salts, among the following is

(a) $\mathrm{SrSO}_4$

(b) $\mathrm{Mg}\left(\mathrm{NH}_4\right) \mathrm{PO}_4$

(c) $\mathrm{BaCrO}_4$

(d) $\mathrm{Mn}(\mathrm{OH})_2$

(e) $\mathrm{PbSO}_4$

(f) $\mathrm{PbCrO}_4$

(g) $\mathrm{AgBr}$

(h) $\mathrm{PbI}_2$

(i) $\mathrm{CaC}_2 \mathrm{O}_4$

(j) $\left[\mathrm{Fe}(\mathrm{OH})_2\left(\mathrm{CH}_3 \mathrm{COO}\right)\right]$

Total number of deactivating groups in aromatic electrophilic substitution reaction among the following is _______ .

The potential for the given half cell at $298 \mathrm{~K}$ is (-) __________ $\times 10^{-2} \mathrm{~V}$

$$ \begin{aligned} & 2 \mathrm{H}_{(\mathrm{aq})}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_2(\mathrm{~g}) \\\\ & {\left[\mathrm{H}^{+}\right]=1 \mathrm{M}, \mathrm{P}_{\mathrm{H}_2}=2 \mathrm{~atm}} \end{aligned} $$

(Given : $2.303 \mathrm{RT} / \mathrm{F}=0.06 \mathrm{~V}, \log 2=0.3$ )

Among the following oxides of p-block elements, number of oxides having amphoteric nature is ________.

$\mathrm{Cl}_2 \mathrm{O}_7, \mathrm{CO}, \mathrm{PbO}_2, \mathrm{~N}_2 \mathrm{O}, \mathrm{NO}, \mathrm{Al}_2 \mathrm{O}_3, \mathrm{SiO}_2, \mathrm{~N}_2 \mathrm{O}_5, \mathrm{SnO}_2$