Atomic number means

An element has an atomic mass of $19$ and an atomic number of $9$. How can its ion be represented?

How many neutrons are present in the nucleus of $_{88}Ra^{226}$?

Match the following species with their respective number of electrons:
| Species | Number of electrons |
| :--- | :--- |
| $(a)$ $O^{2-}$ | $(i)$ $18$ |
| $(b)$ $Li^{2+}$ | (ii) $2$ |
| $(c)$ $He$ | (iii) $10$ |
| $(d)$ $Ca^{2+}$ | (iv) $1$ |

An isotone of $_{32}^{76}Ge$ is (one or more are correct)

What are $_{17}^{35}Cl$ and $_{17}^{37}Cl$? Why?