The number of ions from the following that are expected to behave as oxidising agent is :

$$\mathrm{Sn}^{4+}, \mathrm{Sn}^{2+}, \mathrm{Pb}^{2+}, \mathrm{Tl}^{3+}, \mathrm{Pb}^{4+}, \mathrm{Tl}^{+}$$

The correct arrangement for decreasing order of electrophilic substitution for above compounds is :

During the detection of acidic radical present in a salt, a student gets a pale yellow precipitate soluble with difficulty in $$\mathrm{NH}_4 \mathrm{OH}$$ solution when sodium carbonate extract was first acidified with dil. $$\mathrm{HNO}_3$$ and then $$\mathrm{AgNO}_3$$ solution was added. This indicates presence of :

Consider the given reaction, identify the major product P.