What is the general formula for a secondary amine? rnh2 h2nrnh2 rn2h r2nh

Amines are those organic compounds which are derived from ammonia.
When ammonia is reacted with alkyl halide it produces corresponding amines.

For example,

NH₃  +  R-X → R-NH₂  +  HX (The amine formed is primary amine)

R-NH₂  +  R-X  →  R-NH-R  + HX (secondary amine)

R-NH-R  + R-X  → R₃N  +  HX (tertiary amine)

So,
      Primary Amines are those in which Nitrogen is attached to 1 carbon or nitrogen is attached to two hydrogens.

      Secondary Amines are those in which Nitrigen atom is attached to 2 carbons or Nitrogen is attached to one hydrogen.

      Tertiary Amines are those in which Nitrogen is attached to 3 carbons or there is no hydrogen attached to Nitrogen.

Result:
             R₂NH is the formula for a secondary Amine.