How many protons (p)and neutrons (n)are in an atom ofSr?
A)38 p,52 n
B)38 p,90 n
C)52 p,38 n
D)90 p,38 n

Question

How many protons (p)and neutrons (n)are in an atom ofSr?
A)38 p,52 n 
B)38 p,90 n 
C)52 p,38 n 
D)90 p,38 n

Quizplus · Accepted Answer

The atomic number of an element (in this case, strontium) corresponds to the number of protons in its nucleus. The subscript 38 in the symbol TB6106_11Sr indicates that there are 38 protons. The mass number (or atomic mass) is the sum of the protons and neutrons in the nucleus. The superscript 90 in the symbol represents the mass number, so to find the number of neutrons, we subtract the atomic number from the mass number:

90 (mass number) - 38 (atomic number) = 52 neutrons

Therefore, the correct answer is A) 38 p, 52 n.

How Many Protons (P)and Neutrons (N)are in an Atom Sr