The gold numbers of protective colloids A,B,C and D are 0.04, 0.004, 10 and 40 respectively . The protective powers of A,B,C and D are in the orders .

Options

A. `AgtBgtCgtD`
B. `B gt A gt C gt D`
C. `D gt C gt A gt B `
D. `D gt C gt B gt A `

Answer

To solve the problem regarding 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 of a protective colloid is a measure of its protective power. It indicates the amount of colloid required to protect a certain amount of gold from precipitation. A lower gold number signifies a higher protective power.

### Step 2: List the Gold Numbers
The gold numbers for the colloids are as follows:
- A: 0.04
- B: 0.004
- C: 10
- D: 40

### Step 3: Determine the Protective Power
Since the gold number is inversely proportional to the protective power, we can determine the protective power based on the gold numbers:
- Lower gold number = Higher protective power
- Higher gold number = Lower protective power

### Step 4: Arrange Gold Numbers in Increasing Order
To find the order of protective powers, we first arrange the gold numbers in increasing order:
1. B: 0.004 (highest protective power)
2. A: 0.04
3. C: 10
4. D: 40 (lowest protective power)

### Step 5: Write the Corresponding Protective Powers
Based on the increasing order of gold numbers, we can write the order of protective powers:
1. B (highest protective power)
2. A
3. C
4. D (lowest protective power)

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

### Conclusion
The correct answer, based on the options provided, is that the protective powers of A, B, C, and D are in the order: **B > A > C > D**.

---