The gold number of protective colloids A,B,C and D are 0.02, 0.002, 10 and 30 respectively. then the protective powers of A,B,C and D are in the order

Options

A. `DgtCgtAgtB`
B. DgtCgtBgtA
C. AgtBgtCgtD
D. `BgtAgtCgtD`

Answer

To determine the protective powers of colloids A, B, C, and D 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 required to prevent the coagulation of a certain volume of gold sol when a specific amount of NaCl is added. A lower gold number indicates a higher protective power.

### Step 2: List the Gold Numbers
We have the following gold numbers for colloids A, B, C, and D:
- Gold number of A = 0.02
- Gold number of B = 0.002
- Gold number of C = 10
- Gold number of D = 30

### Step 3: Compare the Gold Numbers
To determine the protective power, we need to compare the gold numbers:
- A: 0.02
- B: 0.002
- C: 10
- D: 30

### Step 4: Determine the Protective Power Order
Since the protective power is inversely proportional to the gold number, we can arrange the colloids in order of their protective powers from highest to lowest:
- B (0.002) has the highest protective power.
- A (0.02) has the next highest protective power.
- C (10) has lower protective power.
- D (30) has the lowest protective power.

### Step 5: Final Order of Protective Powers
Thus, the order of protective powers of colloids A, B, C, and D is:
**B > A > C > D**