Question

An atom has the electronic configuration of $1s^2,2s^2,2p^6,3s^{2}3p^{6}3d^{10},4s^{2}4p^2$. Its atomic weight is $80$. Its atomic number and the number of neutrons in its nucleus shall be:-

• A. $35$ and $45$
• B. $45$ and $35$
• C. $40$ and $40$
• D. $30$ and $50$

Answer 1

Answer: (A)

$35$ and $45$

${}_{35}B{r}^{80}=1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^5$

$A=80,Z=35,N=?$

$N=A-Z=80-35=45$

Atomic number (Proton) is $35$ and no. of neutron is $45$.