Chemistry - GOC Question with Solution | TestHub

(b) - in the cis isomer the second amino group sits close to the first, so after monoprotonation it forms a strong intramolecular hydrogen bond with the $\mathrm{N}{\mathrm{H}}_3^{+}$ group, stabilising the conjugate acid

(a) - the trans arrangement keeps $\mathrm{N}{\mathrm{H}}_2$ and $\mathrm{N}{\mathrm{H}}_3^{+}$ apart, lowering charge-dipole repulsion

(a) - the two amino groups cannot interact, so both lone pairs remain fully available

Both are equally basic because they have the same connectivity