By which of the following, one mol of Silver Iodide/Ag+ sol is coagulated
(a)1 mol of `Kl`
(b)`500mL` of `1MK_(2)SO_(4)`
(c)`300mL` of `1MNa_(3)PO_(4)` solution
(d)1 mol of `Agl`

Options

A. 1 mol of `Kl`
B. `500mL` of `1MK_(2)SO_(4)`
C. `300mL` of `1MNa_(3)PO_(4)` solution
D. 1 mol of `Agl`

Answer

To determine which option can coagulate one mole of Silver Iodide (AgI) sol, we need to consider the principles of coagulation in colloidal solutions. Coagulation occurs when ions that are common to the sol are added, leading to the neutralization of the charges on the colloidal particles.

### Step-by-Step Solution:

1. **Understanding Coagulation**: Coagulation of a colloidal solution occurs when ions that are common to the sol are introduced. In this case, we have a sol of Silver Iodide (AgI), which consists of Ag+ ions and I- ions.

2. **Analyzing the Options**:
- **(a) 1 mol of KCl**: Potassium iodide (KI) dissociates into K+ and I- ions. The I- ions are common with the AgI sol, which can lead to coagulation.
- **(b) 500 mL of 1M K2SO4**: This solution provides K+ and SO4^2- ions. There are no common ions with AgI, so this option cannot cause coagulation.
- **(c) 300 mL of 1M Na3PO4**: This solution provides Na+ and PO4^3- ions. Again, there are no common ions with AgI, so this option cannot cause coagulation.
- **(d) 1 mol of AgI**: Adding more AgI does not introduce any new ions to the system; it simply adds to the existing AgI, thus it cannot cause coagulation.

3. **Conclusion**: The only option that introduces common ions (I-) to the AgI sol is (a) 1 mol of KCl. Therefore, this is the correct answer for coagulating the AgI sol.

### Final Answer:
The correct option is **(a) 1 mol of KCl**.

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