4. Answer briefly I

 

Atoms can combine by transferring valence neutronselectrons protons from one atom to another or by sharing valence electrons to achieve the stable diatomic gasenoble gas triatomic gasemonoatomic gase electronic configuration.

 

 

NaCl is an coordinatemetallicionic covalent compound that is soluble in polar solvents such as water but not non-polar solvents such as benzene (\(C_6H_6\)) or carbon tetrachloride (\(CCl_4\)). Because (\(CCl_4\)) is an metallicinorganic organic non-metallic  compound, hence it is insoluble in water.