To which block does an element with the electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^1$ belong in the periodic table?

In which of the following species,the ratio of $s$-electrons to $p$-electrons is the same?

How many electrons are present in an atom with atomic number $Z = 104$ for which $(n + l) = 8$?

Consider the following sets of quantum numbers. Which of the below settings is not a permissible arrangement of electrons in an atom?

The number of electrons that can be accommodated in $d_{z^2}$ orbital is

Arrange the following in the increasing order of their energy:
$(i)$ $n = 2, l = 0, m_l = 0, m_s = +\frac{1}{2}$
$(ii)$ $n = 2, l = 1, m_l = +1, m_s = -\frac{1}{2}$
$(iii)$ $n = 3, l = 2, m_l = +1, m_s = -\frac{1}{2}$
$(iv)$ $n = 3, l = 1, m_l = -1, m_s = +\frac{1}{2}$