The energy required (in eV) to excite an electron of H -atom from the ground state to the third state is

An element '$$X$$' with the atomic number 13 forms a complex of the type $$[\mathrm{XCl}(\mathrm{H}_2 \mathrm{O})_5]^{2+}$$. The covalency and oxidation state of $$X$$ in it are respectively

In which of the following oxides of three elements $$X, Y$$ and $$Z$$ are correctly arranged in the increasing order of acidic nature. The electronic configurations of $$X, Y$$ and $$Z$$ are $$[\mathrm{Ne}] 3 s^2 3 p^1, [\mathrm{Ne}] 3 s^2 3 p^5$$. [Ne] $$3 s^2$$ respectively

In the Lewis dot structure of carbonate ion shown under the formal charges on the oxygen atoms 1, 2 and 3 are respectively