Question

the mass number of fe²⁺ is 56. how many neutrons are there in a single fe²⁺ atom?
28
30
56
58

Explanation:

Step1: Recall atomic number of iron

Atomic number of Fe is 26.

Step2: Use mass - number formula

Mass number = protons + neutrons.

Step3: Calculate number of neutrons

Neutrons = mass number - protons. Given mass number = 56 and protons = 26, so neutrons = 56 - 26 = 30.

Answer:

B. 30