Phosphorus oxoacids with a \( \text{P-H} \) bond act as reducing agents and can reduce \( \text{AgNO}_3 \) to silver (\( \text{Ag} \)), producing a silver mirror.
Among the given options, \( \text{H}_4\text{P}_2\text{O}_5 \) contains a \( \text{P-H} \) bond, which makes it capable of reducing \( \text{AgNO}_3 \).
The reaction mechanism involves the oxidation of the oxoacid, with the \( \text{P-H} \) bond breaking and silver (\( \text{Ag} \)) being reduced.
The silver forms a mirror on the surface of the reaction vessel.
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).

The method that is based on the difference in oxidation number of oxidizing agent and the reducing agent is known as oxidation number. The half-reaction method entirely depends on the division of the redox reactions into oxidation half and reduction half. It entirely depends on the individual which method to choose and use.
Like various other reactions, it is very important to write the correct compositions and formulas. A very important thing to keep in mind while writing oxidation-reduction reactions is to write the compositions and formulas of the substances and the products present in the chemical reaction in a very correct manner.
In this procedure, we decouple the equation into two halves. After that, we balance both the parts of the reaction separately. Finally, we add them together to get a balanced equation.