What is the formal charge of oxygen atoms in carbon monoxide?

Which of the following statements are true?

Which of the following statements is incorrect?
$(i)$ $NaCl$,being an ionic compound,is a good conductor of electricity in the solid state.
$(ii)$ In canonical structures,there is no difference in the arrangement of atoms.
$(iii)$ Hybrid orbitals form stronger bonds than pure orbitals.
$(iv)$ $VSEPR$ theory can explain the square planar geometry of $XeF_4$.

Which one of the following is different from others with respect to hydrolysis?

What is the structure of $BeCl_2$ molecule in gaseous and solid state?

Which of the following molecules contains both ionic and covalent bonds?