Question

fluorines atomic number is 9 and its atomic mass is 19. how many neutrons does fluorine have?
28
19
81
10
9
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part d
an uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. how many protons does boron have?
5
6
16
11
0

Explanation:

Step1: Recall neutron - proton relationship

The formula for calculating the number of neutrons $n$ is $n = \text{Atomic mass}-\text{Atomic number}$.

Step2: Calculate neutrons in fluorine

For fluorine, atomic number $Z = 9$ and atomic mass $A=19$. So $n=A - Z=19 - 9 = 10$.

Step3: Recall proton - atomic number relationship

The atomic number of an element is equal to the number of protons in an un - charged atom of that element.

Step4: Determine protons in boron

For boron, the atomic number $Z = 5$. So the number of protons is 5.

Answer:

For the first question about fluorine: D. 10
For the second question about boron: A. 5