The gold number of three substances A , B and C are 0.05 , 0.8 and 0.3 . The substance with maximum protective power is

Options

A. A
B. B
C. C
D. All of these

Explanation

To determine which substance has the maximum protective power based on their gold numbers, we can follow these steps:

### Step 1: Understand the Gold Number
The gold number is defined as the minimum weight of a protective colloid (in milligrams) required to prevent the coagulation of a standard hydrosol when a specific amount of electrolyte is added. A lower gold number indicates a higher protective power of the colloid.

### Step 2: Identify the Gold Numbers
We have the following gold numbers for substances A, B, and C:
- Gold number of A = 0.05
- Gold number of B = 0.8
- Gold number of C = 0.3

### Step 3: Compare the Gold Numbers
To find out which substance has the maximum protective power, we need to compare the gold numbers:
- A has a gold number of 0.05
- B has a gold number of 0.8
- C has a gold number of 0.3

### Step 4: Determine the Maximum Protective Power
Since a lower gold number indicates higher protective power, we can conclude:
- A (0.05) has the lowest gold number, which means it has the highest protective power.
- B (0.8) has the highest gold number, indicating it has the lowest protective power.
- C (0.3) is in between A and B.

### Conclusion
The substance with the maximum protective power is **A**, as it has the lowest gold number of 0.05.

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