Question

If A $=$ atomic mass, Z $=$ number of protons, n $=$ number of neutrons, then:

• A. $n=A+Z$
• B. $n=A-Z$
• C. $n=A\times Z$
• D. $n=\frac{A}{Z}$

Answer 1

Answer: (B)

$n=A-Z$

$A$= atomic mass

$Z$= number of protons= number of electrons

$n$= number of neutrons

$n=A-Z$

Example:- Chlorine ${⟶}_{17}^{35}Cl$

$n=A-Z$

$=35-17$

$=18$

(i) Number of protons= Number of electrons= $17$

[Neutral atoms has same number of electron and proton]

(ii) Number of neutron= $18$.