Question

Ar\(^ {18}_{40}\) and Ca\(^ {40}_{20}\) are considered as:

• A. Isobars
• B. Isomers
• C. Isotopes
• D. Isotones

Hint:

Isotopes of an element have the same number of protons (atomic number) but differ in the number of neutrons, leading to different mass numbers.

Answer 1

The Correct Option is A

• Option 1: Isobars - This is the correct answer. Ar-40 and Ca-40 are isobars because they have the same mass number (40) but different atomic numbers (18 for Ar and 20 for Ca). Isobars are atoms of different elements that have the same mass number.
• Option 2: Isomers - This is incorrect. Isomers are molecules with the same molecular formula but different structural arrangements, which is not applicable to the case of Ar and Ca.
• Option 3: Isotopes - This is incorrect. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Ar and Ca are different elements, so they cannot be isotopes of each other.
• Option 4: Isotones - This is incorrect. Isotones are atoms of different elements that have the same number of neutrons but different atomic numbers. Ar and Ca do not fit this definition because their numbers of neutrons are different.

Explanation: 

Ar-40 and Ca-40 are considered isobars because they have the same mass number (40) but different atomic numbers (18 for Ar and 20 for Ca). Isobars are atoms of different elements that share the same mass number but have different atomic numbers.