Draw the product you expect from the reaction of (R)-2-bromooctane with -CN. Use the wedge/hash bond tools to indicate stereochemistry where it exists. Include H atoms at chiral centers only. If a group is achiral, do not use wedged or hashed bonds on it.

See explanation and image attached

Explanation:

The reaction between (R)-2-bromooctane and -CN^- is an SN2 reaction. An SN2 reaction involves a synchronous attack of the nucleophile as the leaving group is departing.

This leads to a five member transition state in which a bond is being broken and another is being made. Since the nucleophile attacks from the backside, SN2 mechanism leads to inversion of configuration as shown in the image attached.

the answer for sodium is 0.186

the answer for rubidium is 0.251

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be