Gold numbers of some colloids are : Gelatin : `0.005-0.01`,Gum Arabic :`0.15-0.25`, Oleate :`0.04-1.0`, Starch `:15-25`. Which among these is a better protective Colloid ?

Options

A. A
B. B
C. C
D. D

Answer

To determine which colloid among the given options is a better protective colloid, we can follow these steps:

### Step 1: Understand the Concept of Gold Number
The gold number is a measure of the protective power of a colloid. It indicates the amount of a protective colloid required to prevent the coagulation of a certain amount of gold sol. A lower gold number signifies a higher protective power.

### Step 2: List the Gold Numbers
The gold numbers for the given colloids are:
- Gelatin: 0.005 - 0.01
- Gum Arabic: 0.15 - 0.25
- Oleate: 0.04 - 1.0
- Starch: 15 - 25

### Step 3: Identify the Lowest Gold Number
From the list, we can identify the lowest gold number:
- Gelatin has the lowest gold number (0.005 - 0.01).

### Step 4: Compare the Gold Numbers
Since the protective power is inversely proportional to the gold number, we can conclude:
- Gelatin (0.005 - 0.01) has the highest protective power.
- Gum Arabic (0.15 - 0.25) has a moderate protective power.
- Oleate (0.04 - 1.0) has lower protective power than Gelatin but higher than Gum Arabic.
- Starch (15 - 25) has the lowest protective power.

### Step 5: Conclusion
Based on the analysis, Gelatin, having the lowest gold number, is the better protective colloid among the options provided.

### Final Answer
The better protective colloid is **Gelatin**.

---