Nuclei with the same mass number but different atomic numbers are called isobars. Consider Ca-40, Ca-41, K-41 and Ar-41. (a) Which of these are isobars? Which are isotopes? (b) What do Ca-40 and Ca-41 have in common? (c) Correct the statement (if it is incorrect) : Atoms of Ca-41, K-41, and Ar-41 have the same number of neutrons.

Part a:

Isobars: Ca-41, K-41 and Ar-41

Part b:

Number of proton

Part c:

Incorrect statement

Explanation:

Part a:

Nuclei with same mass number are called isobars.

Given:

Ca-40, Ca-41, K-41 and Ar-41

Ca-41, K-41 and Ar-41 have equal mass numbers, so these are isobars.

Part b:

Atomic number of Ca = 20

Atomic no. = Number of proton.

So, Ca-40 ans C-41 have same number of proton or in other words proton count is common in both.

Part c:

Number of neutrons in Ca-41

Atomic number = 20

Mass number = 41

Number of neutron = Mass number - atomic number

= 41 - 20 = 21

Number of neutrons in K-41

Atomic number = 19

Mass number = 41

Number of neutron = Mass number - atomic number

= 41 - 19 = 22

Number of neutrons in Ar-41

Atomic number = 18

Mass number = 41

Number of neutron = Mass number - atomic number

= 41 - 18 = 23

So, the statement is incorrect.