The lime water test for $\mathrm{CO_2}$—

1. lime water turns turbid as $\mathrm{CaCO_3}$ is formed
2. excess $\mathrm{CO_2}$ turns the turbid solution opaque due to $\mathrm{Ca(HCO_3)_2}$
3. lime water turns red

• ai and ii
• bii and iii
• ci and iii
• di, ii and iii