6AgNO4(aq) + PH3(g) + 3H2O(l) → 6Ag(s) + H3PO3(g) + 6HNO3(aq) In the above reaction, the reducing agent is

Answer Details

The reducing agent in a chemical reaction is the substance that causes another substance to be reduced, or to undergo a decrease in oxidation state. In the given chemical reaction, we can see that silver ions (Ag+) are being reduced to elemental silver (Ag), indicating that some other substance is causing the reduction to occur. Looking at the reaction, we can see that the substance that fits this description is PH3 (phosphine gas), which is being oxidized (its oxidation state is increasing) and thus acting as a reducing agent. Therefore, the answer is "PH3(g)".