Question

The relation between atomic number (Z) and atomic mass (A) for light elements is given by :

• A. $A=Z$
• B. $A=2Z$
• C. $2A=Z$
• D. $A=4Z$

Answer 1

The correct option is B $A=2Z$

Atomic number (Z) is total no of proton present in nucleus and atomic mass (A) is total no of proton and neutron present in nucleus.
For light atoms till atomic number 20, generally atomic mass is twice the atomic number
$A=2Z$ as $n=p$