Question

Can we write atomic mass of cl as 36 or 35.5 as we round it

Answer 1

Atomic mass is the average of all the isotopes of the element. Usually all the elements atomic mass is calculated in the same way and the decimal figures are rounded off.

But the naturally occurring isotopes of chlorine Cl 35 (75.77%) and Cl 37(24.23%) are relatively present in the ratio 3:1 quite large amount than other elements, hence giving chlorine atomic mass 35.45 approximately 35.5.