\textbf{221 --} In how many cases below do the two compounds mix with each other?
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\textit{[Figure: Four cases each showing two molecular structures:
Case (1): cyclopentane with N substituent (pyrrolidine derivative) and $\mathrm{NH_2}$-terminated chain; and a dichloride compound $\mathrm{Cl_2}$ on a branched carbon.
Case (2): $\mathrm{H_2N}$-chain with carbonyl and $\mathrm{OH}$ group ($\mathrm{HOOC}$, $\mathrm{NH_2}$); and a cyclopentane with a vinyl group.
Case (3): shown structures.
Case (4): shown structures.]}
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(1) 1 \qquad (2) 2 \qquad (3) 3 \qquad (4) 4
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