An isotope has an atomic number of 15 and a mass number of 31. The number of protons it contains is
Answer Details
The atomic number of an element is equal to the number of protons in its nucleus. Therefore, if an isotope has an atomic number of 15, it means it has 15 protons. The mass number of an isotope is equal to the total number of protons and neutrons in its nucleus. The question states that the isotope has a mass number of 31. So, we can write:
mass number = number of protons + number of neutrons
31 = 15 + number of neutrons
To solve for the number of neutrons, we can subtract 15 from both sides:
31 - 15 = 15 + number of neutrons - 15
16 = number of neutrons
Therefore, the isotope with an atomic number of 15 and a mass number of 31 contains 15 protons. Answer is correct.