Which of the following is the strongest reducing agent?

In the reaction $PCl_3 + Cl_2 \to PCl_5$,

The metal which can be used to obtain metallic $Cu$ from aqueous $CuSO_{4}$ solution is

Which of the following may act as both an oxidising and a reducing agent?

Sulphur dioxide and hydrogen peroxide can act as both oxidizing and reducing agents in their reactions,while ozone and nitric acid act only as oxidants. Why?

$A$ reducing agent is a substance which can