Question
Correct the increasing order of acidity is as
A.
$${H_2}O,{C_2}{H_2},{H_2}C{O_3},phenol$$
B.
$${C_2}{H_2},{H_2}O,{H_2}C{O_3},phenol$$
C.
$$phenol,{C_2}{H_2},{H_2}C{O_3},{H_2}O$$
D.
$${C_2}{H_2},{H_2}O,phenol\,{\text{and}}\,{H_2}C{O_3}$$
Answer :
$${C_2}{H_2},{H_2}O,phenol\,{\text{and}}\,{H_2}C{O_3}$$
Solution :
$${C_2}{H_2}$$ have acidic nature but it is less acidic than water. Phenol is more acidic than water due to resonance stabilisation of phenoxide ion. $${H_2}C{O_3}$$ is most acidic due to resonating stabilisation of carbonate ion $$\left( {CO_3^{2 - }} \right).$$
Thus, the correct order is
$${C_2}{H_2} < {H_2}O < phenol < {H_2}C{O_3}$$