The energy associated with electron in first orbit of hydrogen atom is $-2.18 \times 10^{-18} \mathrm{~J}$. The frequency of the light required (in Hz ) to excite the electron to fifth orbit is ( $h=6.6 \times 10^{-34} \mathrm{Js}$ )

In $\mathrm{Sr}(Z=38)$, the number of electrons with $l=0$ is $x$, number of electrons with $l=2$ is $y \cdot(x-y)$ is equal to ( $l=$ Azimuthal quantum number)

$$ \text { Match the following. } $$

The correct answer is

Observe the following data ( $\Delta_t H_1, \Delta_t H_2$ and $\Delta_{\mathrm{eg}} H$ represent the first, second ionisation enthalpies and electron gain enthalpy respectively)

Using the data identify the most reactive metal.