Question

question 8 (1 point)
what is the atomic mass (in amu) for an element with 15 protons and 15 electrons?

a) 15

b) 30

c) 30.97

d) none of the above

Explanation:

Step1: Identify the element

An element with 15 protons has an atomic number of 15, which is phosphorus (P). In a neutral atom, the number of electrons equals the number of protons, so 15 electrons confirm it's a neutral phosphorus atom.

Step2: Recall atomic mass composition

Atomic mass (in amu) is approximately the sum of protons and neutrons. For phosphorus, the most common isotope has 15 protons and 16 neutrons (since atomic mass of P is about 30.97, which is the weighted average of its isotopes, but the question might be referring to the mass number or the actual atomic mass). Wait, but let's check: the atomic mass of phosphorus is approximately 30.97 amu. The options: a) 15 (just protons, wrong), b) 30 (15+15, assuming neutrons=15, but P has ~16 neutrons), c) 30.97 which is the actual atomic mass of P.

Answer:

c) 30.97