Which of the following reactions does not form $PCl_3$ as one of the products?

Which of the following represents the correct order of bond energy?

The reaction of $K_2Cr_2O_7$ with $NaCl$ and conc. $H_2SO_4$ gives

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{I}OF_5 + 2H_2O \longrightarrow HIO_4 + 5HF$

Which of the following statements is not true for the reaction $2 F_{2} + 2 H_{2}O \rightarrow 4 HF + O_{2}$?

$A$ solid $A$ which has photographic effect reacts with the solution of a sodium salt $B$ to give a pale yellow precipitate $C$. The sodium salt $B$ on heating with concentrated $H_2SO_4$ gives brown vapours. Identify $A$,$B$,and $C$.