Answer :
Going from left to right, they are ordered by increase in atomic number
Answer: Option (4) is the correct answer.
Explanation:
Atomic mass of an atom or element means the total number of protons and total number of neutrons present.
Whereas atomic number means the total number of protons present in an atom or element.
In period 5 on the Periodic Table, elements from left to right are arranged in order of increasing atomic number.
On the other hand, the atomic mass is not increasing from left to right.