There are sub shells in shells around the nucleus.

Write the possible sub shells in third shell in the increasing order of energy.

There are sub shells in shells around the nucleus.

Which of the following is the outermost electronic configuration of copper? (Atomic number =29)
$$\begin{gathered} \mathrm{A}: 3{\mathrm{d}}^{9}4{\mathrm{s}}^2 \\ \mathrm{B}: 3{\mathrm{d}}^{10}4{\mathrm{s}}^1 \end{gathered}$$

Justify your answer.

The last subshell of an element is 3p and there are 3 electrons in it. 

Write the complete electronic configuration of the element.

The last subshell of an element is 3p and there are 3 electrons in it. 

Identify its period and group. 

The atomic number of an element is 19.

Write the subshell electronic configuration. 

The atomic number of an element is 19.

Identify its group, period, block and oxidation state.

The atomic number of an element is 19.

Write any one characteristic of the block to which the element belongs. 

Select the correct subshell configuration of  ${}_{24}\mathrm{Cr}$ from the following:

(i) $1{\mathrm{s}}^2 2{\mathrm{s}}^2 2{\mathrm{p}}^6 3{\mathrm{s}}^2 3{\mathrm{p}}^6 3{\mathrm{d}}^{4 }4{\mathrm{s}}^2$

(ii) $1{\mathrm{s}}^2 2{\mathrm{s}}^2 2{\mathrm{p}}^6 3{\mathrm{s}}^2 3{\mathrm{p}}^6 3{\mathrm{d}}^5 4{\mathrm{s}}^1$