yellow phosphorus on reaction with `Ca(OH)_(2)` gives:

Options

A. `Ca(H_(2)PO_(4))_(2)`
B. `Ca(H_(2)PO_(2))_(2)`
C. `PH_(3)`
D. ` PH_(5)`

Explanation

To determine the products of the reaction between yellow phosphorus and calcium hydroxide, we can follow these steps:

### Step 1: Write the Reactants
We start with yellow phosphorus, which is represented as \( P_4 \), and calcium hydroxide, represented as \( Ca(OH)_2 \). The reaction also requires water, \( H_2O \), to proceed.

### Step 2: Write the Reaction
The reaction can be written as:
\[ P_4 + Ca(OH)_2 + H_2O \rightarrow \text{Products} \]

### Step 3: Identify the Products
Upon reaction, yellow phosphorus reacts with calcium hydroxide in the presence of water to produce calcium hypophosphite and phosphine. The products can be represented as:
- Calcium hypophosphite: \( Ca(H_2PO_2)_2 \)
- Phosphine: \( PH_3 \)

### Step 4: Write the Balanced Equation
To balance the equation, we need to ensure that the number of each type of atom is the same on both sides of the equation.

1. Start with the phosphorus atoms:
- On the left, we have 4 phosphorus atoms from \( P_4 \).
- On the right, we will have to balance it with \( Ca(H_2PO_2)_2 \) and \( PH_3 \).

2. Balancing the phosphorus:
- If we use 2 \( Ca(H_2PO_2)_2 \), that gives us 4 phosphorus atoms.
- We can also produce 2 \( PH_3 \) for additional phosphorus.

3. Balancing the calcium and hydroxide:
- For every 2 \( Ca(H_2PO_2)_2 \), we need 2 \( Ca(OH)_2 \) to provide the calcium and hydroxide ions.

4. Balancing the hydrogen and oxygen:
- Count the hydrogen from \( Ca(OH)_2 \) and \( H_2O \) to ensure they match with the products.

The balanced equation looks like this:
\[ P_4 + 4 Ca(OH)_2 + 2 H_2O \rightarrow 2 Ca(H_2PO_2)_2 + 2 PH_3 \]

### Final Products
Thus, the products of the reaction between yellow phosphorus and calcium hydroxide are:
- Calcium hypophosphite: \( Ca(H_2PO_2)_2 \)
- Phosphine: \( PH_3 \)

### Summary
Yellow phosphorus reacts with calcium hydroxide to yield calcium hypophosphite and phosphine.

---