Choose the correct order arranged in decreasing order of basicity.

The correct order of increasing basicity of the given conjugate bases $( \mathrm{R}={\mathrm{CH}}_3)$  is

Which of the following statements about ${{\mathrm{HCO}}_3}^{-}$ are correct?

$1$. It is a Bronsted acid.

$2$. It can ionize in water to form ${{\mathrm{CO}}_3}^{2-}\left(\mathrm{aq}\right)$.

$3$. It does not exist in aqueous solution.

$4$. It is a Bronsted base.

Select the correct answer using the codes given below.

The strongest conjugate base is