Ask a New Question
Menu

A neutral atom of potassium (K) has an average mass of 39 amu and 19 electrons. How many neutrons does it have?

Group of answer choices

58

19

20

10

1 answer

To find the number of neutrons in a neutral atom of potassium (K), we can use the formula:

\[ \text{Number of neutrons} = \text{Mass number} - \text{Number of protons} \]

  1. The mass number (approximately equal to the average atomic mass rounded to the nearest whole number) of potassium is 39.
  2. The number of protons in potassium is equal to the number of electrons in a neutral atom, which is 19.

Now, substituting these values into the formula:

\[ \text{Number of neutrons} = 39 - 19 = 20 \]

Thus, the number of neutrons in a neutral atom of potassium is 20. Therefore, the correct answer is:

20