Question

What element has a mass number of 40 and 20 protons?

Answer 1

Hint: The atomic number of an element will give the information about the number electrons and number of protons present in the given element. From the mass number and number of protons we can calculate the number of neutrons present in the given element.

Complete answer:
 - In the question it is asked to find the element which has a mass number of 40 and has 20 protons in it.
- In the question it is given that an element has a mass number of 40 and number of protons are 20.
- We know that mass number = number of protons + number of neutrons.
Mass number = 40
Number of protons = 20
- Therefore the number of neutrons = 40 – 20 = 20 neutrons.
- It is given that the element has 20 protons means the element contains 20 electrons.
- The element has 20 electrons means the atomic number of the element is 20.
- Therefore the atomic number of the element is 20.
- The element which contains 20 electrons in the periodic table is Calcium.
- Therefore the element which contains 20 protons and 20 electrons with a mass number of 40 is calcium.

Note:
By knowing the number of neutrons, number of electrons, and number of protons we can easily find the name of the particular element. Every element has a specific atomic number. Atomic number for all the elements in the periodic table is not going to match.