20 1 1 year CCTV "3? 15 special program "exposure: The illegal drug" Clenbuterol "is used in the main pig producing areas of Henan Province. The scientific name of" Clenbuterol "is Dichlorohydrochloride. A, according to the chemical formula of "Clenbuterol" is C 12 H 18 Cl 2 N 2 O, it is known that it is composed of five elements: carbon, hydrogen, chlorine, nitrogen and oxygen, so A is correct;

B, the chemical formula of "Clenbuterol" is C 12 H 18 Cl 2 N 2 O, in which the mass fraction of each element is equal to the sum of the relative atomic mass of the element divided by the relative molecular mass of the substance, the relative molecular mass of the substance is the same, and the sum of the relative atomic mass of carbon is12 =/kloc. The sum of the relative atomic masses of hydrogen is/kloc-0 /×18 =18, chlorine is 35.5×2=7 1, and nitrogen is14× 2 = 20.

C, organic matter refers to carbon-containing compounds (except carbon oxides, carbonic acid, carbonate), "lean meat" conforms to the definition, so C is correct;

D. According to the chemical formula of "Clenbuterol" as C 12 H 18 Cl 2 N 2 O, it is known that each clenbuterol molecule consists of 12 carbon atoms, 18 hydrogen atoms, 2 chlorine atoms, 2 nitrogen atoms and 1 0 oxygen atoms, and in one molecule, Therefore, D is correct.

So choose B.