Question

An element has an atomic number of $11$ and mass number of $24$. Then nucleus consists of:

• A. $11$ protons, $13$ neutrons
• B. $13$ protons, $11$ neutrons
• C. $11$ protons, $13$ neutrons, $13$ electrons
• D. $13$ protons, $11$ electrons

Answer 1

The correct option is A $11$ protons, $13$ neutrons

$\text{Atomic number = No. of proton}$
$\text{Mass number = No. of proton + No. of neutron}$

Hence the number of protons is $11$, number of electrons is 11 and number of neutrons is $24-11=13$.