An atom which has lost one electron would be

The number of protons,neutrons and electrons in ${}^{13}_{6}C$ respectively are

An element has an atomic weight of $40$ and its electronic configuration is $1s^2 2s^2 2p^6 3s^2 3p^6$. What are its atomic number and the number of neutrons?

$A$: Atoms with the same mass number but different atomic numbers are called isobars.
$R$: In isobars,the sum of protons and neutrons is always different.

Give the relation between the following pairs of species:
$(i)$ $_{20}^{40}Ca$ and $_{19}^{40}K$
$(ii)$ $_{17}^{35}Cl$ and $_{17}^{37}Cl$
$(iii)$ $_{18}^{40}Ar$,$_{20}^{40}Ca$ and $_{19}^{40}K$
$(iv)$ $_{38}^{87}Sr$ and $_{38}^{90}Sr$

An ordinary oxygen sample contains: