Explain why rubbing an alkali like bicarbonate of soda onto an acidic bee sting can ease the pain ?

Because when a bee stings a person it injects an acidic liquid into the skin which causes the pain/irritation, applying baking soda can help neutralize the acidity of the sting easing inflammation

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf