Question

If two similar groups in a projection formulae
are on the same side of the vertical chain
then the isomer is called form.
Answer:
O Erythro
O Trans
O Threo​

Answer 1

Answer:

1.  The higher the atomic number of the immediate substituent atom, the higher the priority.

For example, H–  <  C–  <  N–  <  O–  <  Cl–. (Different isotopes of the same element are assigned a priority according to their atomic mass.)

2.  If two substituents have the same immediate substituent atom,

evaluate atoms progressively further away from the chiral center until a difference is found.

For example, CH3–  <  C2H5–  <  ClCH2–  <  BrCH2–  <  CH3O–.

3.  If double or triple bonded groups are encountered as substituents, they are treated as an equivalent set of single-bonded atoms.

For example, C2H5–  <  CH2=CH–  <  HC≡C–

Explanation:

Answer 2

Answer:

O Threo​IS THE RIGHT ANSWER.