The aqueous solution of carbon dioxide is slightly acidic as it forms carbonic acid.
CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃^-

The equilibrium involved in the reaction between carbon dioxide and hydrogen, has many industrial applications and is called water gas equilibrium.
CO₂ + H₂ ⇌ CO + H₂O
                   water gas

In oxo process, ethene is mixed with carbon monoxide and hydrogen gas to produce propanal.
CO + C₂H₄ + H₂ ⟶ CH₃CH₂CHO

When carbon monoxide is treated with chlorine in presence of light or charcoal, it forms a poisonous gas carbonyl chloride, which is also known as phosgene.
CO + Cl₂ ⟶ COCl₂

(i) It is used for purification of water
(ii) It is also used for water proofing and textiles.
(iii) It is used in dyeing, paper and leather tanning industries.
(iv) It is employed as a styptic agent to arrest bleeding.

On heating to 475 K potash alum loses water of hydration and swells up. The swollen mass is known as burnt alum.

The name alum is given to the double salt of potassium aluminium sulphate.
[K₂SO₄.Al₂(SO₄)₃.24H₂O]

(i) Boron trifluoride is used for preparing HBF₄, a catalyst in organic chemistry
(ii) It is also used as a fluorinating reagent.

Diboranes reacts with water and alkali to give boric acid and metaborates respectively.
B₂H₆+ 6H₂O ⟶ 2H₃BO₃ + 6H₂
B₂H₆+ 2NaOH + H₂O ⟶ 2NaBO₂ + 6H₂

(i) Boranes are colourless diamagnetic compounds with low thermal stability.
(ii) Diborane is a gas at room temperature with sweet smell and it is extremely toxic.
(iii) It is also highly reactive At high temperatures it forms higher boranes liberating hydrogen.

(i) Boric acid reacts with calcium fluoride in presence of conc. sulphuric acid and gives boron trifluoride.
3CaF₂ + 3H₂SO₄ + 2B(OH)₃ ⟶ 3CaSO₄ + 2BF₃ + 6H₂O
(ii) Borax when heated with soda ash it gives borax
Na₂CO₃ + 4B(OH)₃ ⟶ Na₂B₄O₇ +.CO₂ + 6H₂O

Boric acid can be extracted from borax and colemanite.
Na₂B₄O₇ + H₂SO₄ + 5H₂O ⟶ Na₂SO₄ + 4H₃BO₃
Ca₂B₆O₁₁ + 11H₂SO₄ + SO₂ ⟶ Ca(HSO₃)₂ + 6H₃BO₃

In p-block elements, the first member of each group differs from the other elements of the corresponding group. The following factors are responsible for this anomalous behaviour
(i) Small size of the first member.
(ii) High ionisation enthalpy and high electronegativity.
(iii) Absence of d-orbitals in their valance shell.