Select the correct answer. An element has atomic number 10 and an atomic mass of 20. How many neutrons are in the atom of this element? A. 10 B. 20 C. 30 D. 0 E. 200

I may be wrong but I think its 10.

Explanation:

Number of Protons - Atomic mass.

A. 10

Explanation:

The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).

(N) Neutrons = 10

(M) Atomic Mass = 20

(Z) Atomic Number = 10

Z + __ = M

10 + __ = 20

10 + 10 = 20

mistakes are ok

d eras and periods