Question

Question 9

How many neutrons are in an atom of Mg-25?
O 11
O 12
O
13
O 31

Answer 1

number of neutrons = 13.

Explanation:

Each element is uniquely and completely identified by its Atomic Number. This is the number of protons in the nucleus, which is equal to the number of electrons in the neutral atom.The Atomic Number of Magnesium is 12.An atom’s Mass Number is the number of protons plus the number of neutrons in its nucleus.For Mg-25 the Mass Number is 25.So 25 = (number of protons) + (number of neutrons)= 12 + (number of neutrons)

Answer 2

They differ only because a 24Mg atom has 12 neutrons in its nucleus, a 25Mg atom has 13 neutrons, and a 26Mg has 14 neutrons. Figure 2.3.