Naturally occurring chlorine consists of 35Cl (mass 34.96885 amu) and 37Cl (mass 36.96590 amu), with an average mass of 35.453 amu.

The atomic masses of cl 35(75.53 percent) and cl 37 ( 24.47 percent) are 34.968 amu and 36.956 amu.

Chlorine-35 and chlorine-37 are both isotopes of the element chlorine. An atom of chlorine-35 contains 18 neutrons (17 protons + 18 neutrons = 35 particles in the nucleus) while an atom of chlorine-37 contains 20 neutrons (17 protons + 20 neutrons = 37 particles in the nucleus).

Cl-35 and Cl-37 are isotopes i.e. they have same no. Since chemical properties depends on electrons therefore isotopes have same chemical properties. Isotopes differ by their mass number or rather the no. of neutrons present in their nucleus.

Answer : Cl35 and Cl37 will have same valencies. These are two isotopes of Chlorine. The atoms of same elements which have the same atomic numbers but different mass numbers are known as isotopes.

This implies that out of every four atoms of chlorine, there are 3 atoms of Cl-35 and 1 atom of Cl-37. Hence, Cl-35 is more abundant than Cl-37.

24.23%

35.453 u

Sodium-23 | Na – PubChem.

Sodium (Na), chemical element of the alkali metal group (Group 1 [Ia]) of the periodic table. Sodium is a very soft silvery-white metal. Sodium is the most common alkali metal and the sixth most abundant element on Earth, comprising 2.8 percent of Earth’s crust.

Mass number = Total number of protons + Total number of neutrons Sodium atom has 11 protons and 12 neutrons in its nucleus. Thus, we get the atomic mass number 11 + 12 = 23. Na has the atomic mass number 23, so its atomic mass is 23 amu.

Protons and neutrons have similar masses, approximately 1 amu each. Most sodium atoms have 11 protons and 12 neutrons, giving a total of ~23 amu, and dividing by 1 amu then gives 23 for the relative atomic mass.