1 Consider the first atom of each part of the molecule. An atom with higher atomic number has higher priority. (e.g. I > Cl > C > H)  If the first atom of two groups is the same, consider the second atom(s) in the same way as the first. (e.g. -C(CH3)3 > -CH(CH3)2 > -CH2CH3 > -CH3).
1 You can also use a toilet plunger on your bathroom sink. 2  Fill up the sink with water first, the use the plunger vigorously on the drain just as you would a toilet. 3  This will lift and agitate any blockage in the drain. It will smell a bit like vinegar for about a day. 2  You can also use a toilet plunger on your bathroom sink. 3  Fill up the sink with water first, the use the plunger vigorously on the drain just as you would a toilet.
As long as the sink drain and its vent are connected in a straight line, the drain can serve as a wet vent for the toilet. This means, however, that if there's a blockage downstream of the sink, water can back up through the sink pipe. You can get a good idea of the plumbing configuration to which the sink is attached by noting which fixtures make the sink back up when they drain. They may also back up when other fixtures are draining.