White P reacts with caustic soda (NaOH) forming `PH_(3)` and `NaH_(2)PO_(2)`. The reaction is-

Options

A. Redox
B. Oxidation
C. Reduction
D. Neutralisation

Answer

To analyze the reaction of white phosphorus (P4) with caustic soda (NaOH) that produces phosphine (PH3) and sodium hypophosphite (NaH2PO2), we can follow these steps:

### Step 1: Write the balanced chemical equation
The reaction can be represented as follows:

\[ P_4 + 4 NaOH + 2 H_2O \rightarrow 2 PH_3 + 2 NaH_2PO_2 \]

### Step 2: Identify the oxidation states of elements
- In \( P_4 \), phosphorus (P) has an oxidation state of 0.
- In \( PH_3 \), phosphorus has an oxidation state of -3.
- In \( NaH_2PO_2 \), phosphorus has an oxidation state of +1.
- Sodium (Na) in NaOH and NaH2PO2 has an oxidation state of +1.
- Hydrogen (H) in NaOH and PH3 has an oxidation state of +1.
- Oxygen (O) in NaOH and NaH2PO2 has an oxidation state of -2.

### Step 3: Determine changes in oxidation states
- Phosphorus changes from 0 in \( P_4 \) to -3 in \( PH_3 \) (reduction).
- Phosphorus changes from 0 in \( P_4 \) to +1 in \( NaH_2PO_2 \) (oxidation).

### Step 4: Identify oxidation and reduction
- The change from 0 to -3 indicates a gain of electrons (reduction) for the phosphorus in \( PH_3 \).
- The change from 0 to +1 indicates a loss of electrons (oxidation) for the phosphorus in \( NaH_2PO_2 \).

### Step 5: Conclusion about the type of reaction
Since both oxidation and reduction are occurring, this reaction is classified as a redox reaction.

### Final Answer
The reaction of white phosphorus with caustic soda is a redox reaction.

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