Carbonic acid is a polyprotic acid. write balanced chemical equations for the sequence of reactions that carbonic acid can undergo when it's dissolved in water.

Carbonic acid (H₂CO₃) dissociation in water takes place in 2 steps. its a polypro tic acid as it has 2 H⁺ ions it can donate.
the dissociation reactions in water are as follows;
H₂CO₃  + H₂O ---> HCO₃⁻ + H₃O⁺
in the first dissociation it releases a proton that combines with water to form a hydronium ion.
HCO₃⁻ + H₂O  > CO₃²⁻ + H₃O⁺
second dissociation results in the carbonate ion and hydronium ion formation.
As the ratio of acid dissociation constant ka1/ka2 > 10⁴ , dissociation takes place in 2 steps. 

All the elements are arranged by melting points on the periodic table. in row they go from metals to gasses. in the row from sodium to argon, sodium is more reactive than the one on its right, magnesium.

The teacher is mostly talking about the distillation of a mixture