The order of magnitude of the diameter of the earth is (diamtere of the earth is `1.28xx10^(7)m`)
5
6
7
8

Options

A. 5
B. 6
C. 7
D. 8

Explanation

To determine the order of magnitude of the diameter of the Earth, which is given as \(1.28 \times 10^7\) meters, we can follow these steps:

### Step 1: Identify the Scientific Notation
The diameter of the Earth is given in scientific notation as:
\[ D = 1.28 \times 10^7 \text{ meters} \]

### Step 2: Analyze the Coefficient
In scientific notation, the coefficient (the number before the \( \times 10^n \)) is \(1.28\). We need to look at this coefficient to determine the order of magnitude.

### Step 3: Determine the Order of Magnitude
The order of magnitude is determined by the exponent of 10 in the scientific notation. Here, the exponent is \(7\).

### Step 4: Check the Coefficient
Since the coefficient \(1.28\) is less than \(5\), we do not need to add \(1\) to the exponent. If the coefficient were \(5\) or greater, we would add \(1\) to the exponent.

### Conclusion
Thus, the order of magnitude of the diameter of the Earth is:
\[ \text{Order of Magnitude} = 7 \]

### Answer
The correct option is \(7\).

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