sir help me to solve these problems.write the compounds in decreasing order of their co-valent character.1-NH3,PH3,AsH3,SbH3,BiH3.2-H2O,H2S,H2Se,H2Te.3-Li2O,Na2O,K2O,Rb2O,CS2O.4-BeCO3,MgCO3,CaCO3,BaCO3.

Dear student,

The proportion of covalent character in an ionic bond is decided by polarisability of the metal cation as well as the electronegativity of both elements involved in bonding. Polarisability is further decided by the density of positive charge on the metal cation. For instance, NaF is a very stable ionic compound. Na(+) bears only 1 unit of positive charge and sodium is of low electronegativity. Thus Na(+) shows negligible tendency to attract electrons. For F(-), fluorine has a very high electronegativity to keep electrons around itself. Thus, it is presumable that electron cloud in NaF is not so distorted and it has a very large proportion of ionic character. Another opposite example is AlCl3, a considered-covalent compound. This is because Al(3+) bears 3 units of positive charge and shows strong tendency to distort the electron cloud, thus the covalent character in Al-Cl bond dramatically increases and predominates.