The species present in solution when $\mathrm{CO}_2$ is dissolved in water are

• Correct answer
  A

  $\mathrm{CO}_2, \mathrm{H}_2 \mathrm{CO}_3, \mathrm{HCO}_3^{-}, \mathrm{CO}_3^{2-}$
• B

  $\mathrm{H}_2 \mathrm{CO}_3, \mathrm{CO}_3^{2-}$
• C

  $\mathrm{CO}_3^{2-}, \mathrm{HCO}_3^{-}$
• D

  $\mathrm{CO}_2, \mathrm{H}_2 \mathrm{CO}_3$

Solution

When $\mathrm{CO}_2$ is dissolved in water, therefore it forms dibasic carbonic acid, which gives $\mathrm{HCO}_3^{-}$ and $\mathrm{CO}_3^{2-}$ ions on ionisation. Hence in solution $\mathrm{CO}_2, \mathrm{H}_2 \mathrm{CO}_3, \mathrm{HCO}_3^{-}$and $\mathrm{CO}_3^{2-}$ are present.

Hence, the correct answer is option: 'A'.