Question

An atom has a mass number of 37 and atomic number 17. How many protons does it have?

• A. 20
• B. 54
• C. 17
• D. 37

Answer 1

Answer:

C. 17

Given in the question the following data;

• Mass number, A = 37
• Atomic number, Z = 17
• Number of protons = Atomic number = 17

Note:

• Atomic number indicates the total number of protons or electrons.

Z = no. of protons / electrons

• Atomic mass number indicates the sum of protons and neutrons.

A = P + N

However, had the question been to find the number of Neutrons, we could find it by subtracting the atomic number from its mass number.

ie,

Number of Neutrons = A - Z

= 37 - 17

= 20