Among NaCl, `BeCl_2`, and `AlCl_3`, which one is more covalent? Justify the answer.

Which is bigger unit J or eV? Justify for your answer.

a) Which one has greater size, Na or K? b) Justify your answer.

the water solutions of the ionic compounds NaCl, CH_3COONa and NH_4Cl show different pH. Justify your answer.

2Na + H_2 to 2NaH . In this reaction ? Justify your answer.