Question

Atoms of different elements having the same mass number are known as:
A. Isotopes
B. Isobars
C. Isotones
D. Isomers

Answer 1

Hint: The term ‘iso’ means the same. We should know the terms involved in the word to answer the question. The molecular weight or atomic weight of an element is called mass number. Mass number is going to be obtained by doing the sum of the number of protons and neutrons present in the nucleus of the atom.

Complete Solution :
- In the question it is given that the atoms of different elements having the same mass number are called as.
- If the atoms have the same atomic number they are called isotopes.
- If the atoms have the same number of neutrons then they are called isotones.
- If the atoms have the same molecular formula then they are called isomers.
- If the atoms have the same mass number then they are called isobars.
- ‘Iso’ means the same and bar means mass number.
- Means if the atoms of the different elements have the same mass number then they are called isobars.
So, the correct answer is “Option B”.

Note: The examples for isobars (elements with same mass number) are $^{40}S{{,}^{40}}Ca{{,}^{40}}K{{,}^{40}}Ar{{,}^{40}}Cl$ . All these elements Sulphur, calcium, potassium, Argon, Chlorine have the same mass number then they are called as isobars. Mass number of the elements is going to write in the position of superscript to the element and atomic number should be written in the subscript to the element.