Question

1. ca-40, k-39, and sc-41 all have the same (4pts)

□ atomic mass.
□ atomic number
□ number of electrons.
□ number of neutrons.

Explanation:

Step1: Define key atomic properties

Atomic number = number of protons (and electrons in neutral atoms). Atomic mass (mass number) = protons + neutrons. Neutrons = mass number - atomic number.

Step2: Get atomic numbers

Ca (calcium): atomic number = 20; K (potassium): atomic number = 19; Sc (scandium): atomic number = 21.

Step3: Calculate neutron counts

For Ca-40: $40 - 20 = 20$ neutrons
For K-39: $39 - 19 = 20$ neutrons
For Sc-41: $41 - 21 = 20$ neutrons

Step4: Verify other properties

Atomic masses: 40, 39, 41 (different). Atomic numbers: 20,19,21 (different). Electrons = atomic numbers (different).

Answer:

number of neutrons.