`P_4` undergoes disproportionation in basic medium to give `PH_3` (phosphine) and `H_2PO^(ɵ)` (dihydrogen hypophoshite ion). Atomic weight of P is 31.

Explanation

To solve the problem of the disproportionation of \( P_4 \) in a basic medium to form \( PH_3 \) (phosphine) and \( H_2PO_2^- \) (dihydrogen hypophosphite ion), we will follow these steps:

### Step 1: Write the overall reaction
The disproportionation reaction can be represented as:
\[ P_4 \rightarrow PH_3 + H_2PO_2^- \]

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