To prevent rancidification of food material,which of the following is added?

$HNO_2$ acts as which of the following?

What is an oxidising agent and a reducing agent? Explain with examples.

Identify the change in the oxidation state of the oxidising agent in the following redox reaction: $3H_3AsO_3(aq) + BrO_3^-(aq) \rightarrow Br^-(aq) + 3H_3AsO_4(aq)$

Which of the following is not oxidized by $O_3$?

When acidified $K_2Cr_2O_7$ solution is added to $Sn^{2+}$ salts,then $Sn^{2+}$ changes to: