Final answer:
The number 65789 can be expressed in scientific notation as 6.6 × 10⁴ km, rounding to two significant figures and considering the power of 10 that corresponds to the decimal point moved 4 places to the left.
Step-by-step explanation:
To express the number 65789 in scientific notation, we follow the convention that only one non-zero digit should be to the left of the decimal point. Therefore, we move the decimal point 4 places to the left, which will be reflected as a positive exponent in the scientific notation since the original number is greater than 1.
After moving the decimal point, the number becomes 6.5789. We round this to two significant figures because the options given are in that format, so it becomes 6.6. Now, we multiply by 10 raised to the power of 4, because we moved the decimal point 4 places, resulting in the scientific notation 6.6 × 104.
The correct answer from the given options is therefore: