Determine the wavelength of the light absorbed when an electron in a hydrogen atom makes a transition from an orbital in which n=2n=2 to an orbital in which n=7n=7.

i think it is true since you can test the answer and can use observations to complete it.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.