Question

How many geometric isomers are possible for `H_3C-CH_2CHBrCHFCH_2CH_3`?

Answer 1

Are there not FOUR possible geometries......?

Explanation:

For `H_3C-CH_2CHBrCHFCH_2CH_3` are not the substituted carbons, `C3`, and `C4` chiral? And thus with respect to chiral carbons, are there not FOUR possible stereoisomers: `"RR"`; `"RS"`; `"SR"`; and `"SS"`.

In general a molecule with `n` chiral centres can generate up to `2^n` stereoisomers. I qualified this statement with the words `"up to"`, because for some molecules (but not this one), `RS-=SR`, i.e. they are equivalent meso structures, but in the given molecular there is no internal symmetry...

And if you find it hard vizualizing this MAKE A MODEL......

See here for basics...and also here..and here and here.

Don't forget your text, and I reiterate the importance of models.