Question

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

Answer 1

A. 10

Step-by-step 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

Answer 2

I may be wrong but I think its 10.

Step-by-step explanation:

Number of Protons - Atomic mass.