Metal ion in a biological coordination compound (chlorophyll, haemoglobin)

1. A.
   $\mathrm{Mg^{2+}}$
2. B.
   $\mathrm{Ca^{2+}}$
3. C.
   $\mathrm{Fr^+}$
4. D.
   $\mathrm{Na^+}$

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1. A.
   $\mathrm{Ca^{+2}}$
2. B.
   $\mathrm{Co^{+3}}$
3. C.
   $\mathrm{Fe^{+2}}$
4. D.
   $\mathrm{Mg^{+2}}$

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