Question

Which of the following atoms contains the same number of neutrons as an atom of Calcium-40? (2 points) Select one: a. Potassium-40 b. Scandium-44 c. Argon-38 d. Chlorine-36

Answer 1

Answer:

Calcium and Argon both have 20 neutrons.

Explanation:

Atomic number is the number of protons in an element

Mass number is the sum of number of protons and neutrons in an element

So we can calculate the number of neutrons in an element by subtracing atomic number from its mass number.

Atomic number of given elements are:

Ca : 20

Potassium : 19

Scandium : 21

Argon : 18

Chlorine : 17

Let us calculate the number of neutrons in each element.

Ca:

Number of neutrons = Mass number - atomic number = 40-20 = 20

K :

Number of neutrons = Mass number - atomic number = 40-19 = 21

Sc:

Number of neutrons = Mass number - atomic number = 44-21 = 23

Ar:

Number of neutrons = Mass number - atomic number = 38-18 = 20

Cl:

Number of neutrons = Mass number - atomic number = 36-17 = 19

Thus Calcium and Argon both have 20 neutrons.

Answer 2

First, let's find the number of neutrons in Calcium-40. to find the number of neutrons, you need to take the atomic mass minus atomic number

neutrons in Calcium---> 40 - 20 (atomic number) = 20 neutrons

potassium-40---> 40- 19= 21
scandium-44----> 44- 21= 23
argon-38---------> 38- 18= 20
chlorine-36------> 36- 17= 19

the answer is argon-38