An atom of aluminum (al) has an atomic number of 13 and a mass number of 27. how many neutrons does it have?

a) 13
b) 14
c) 27
d) 40

B

Atomic mass = no. of proton

Atomic mass= P +N

27= 13+N

N=14

14

Explanation:

The atomic # is how many protons it has, the mass is the total number of protons (P) and neutrons (N).

P+N=M     13+N=27

27-13=14    Neutrons= 14

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