Cahn-Ingold-Prelog (CIP) priority rules

They are checked sequentially as follows:

Rule 1-Higher atomic number precedes lower
Rule 2-Higher atomic mass precedes lower
Rule 3-cis precedes trans
Rule 4-Like pairs of descriptors precede unlike pairs
Rule 5-R precedes S

Glossary of chemistry in hindi Stereochemistry त्रिविम प्रभाव

Rule Description 1a Higher atomic number precedes lower. Br > Cl > O > N > C > H 1b Inner sphere identical atoms precede outer sphere identical atoms. 2 Higher atomic mass precedes lower. D > H; 13C > 12C; 81Br > 79Br 3 Seqcis precedes Seqtrans; Z precedes E and this precedes non-stereogenic double bonds. 4a Chiral stereogenic units precede pseudoasymmetric stereogenic units which precede non-stereogenic units. 4b Like pair R,R=lk or S,S=lk precedes unlike pair R,S=ul or S,R=ul; and M,M=lk or P,P=lk precedes M,P=ul or P,M=ul; and R,M=lk or S,P=lk precedes R,P=ul or S,M=ul; and M,R=lk and P,S=lk precedes M,S=ul or P,R=ul. 4c 'r' precedes 's'; 'm' precedes 'p'. 5 Atom or group descriptor 'R', 'M' or 'Seqcis' precede 'S', 'P' and 'Seqtrans', respectively.