Final answer:
The diameter of the microbe is 0.00000251 meters, which is expressed in scientific notation as 2.51 x 10^-6 meters.
Step-by-step explanation:
To express the diameter of the microbe, which is 0.00000251 meters, in scientific notation, move the decimal place to the right until you get a number between 1 and 10. In this case, you would move the decimal place six places to the right, giving you 2.51. Because you moved the decimal to the right, the exponent will be negative and equal to the number of places you moved the decimal. Therefore, the diameter of the microbe in scientific notation is 2.51 × 10-6 meters.