Which of the following is true about $C O_{2}$ ?

It is a colourless, odourless and tasteless gas

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

It dissolves in water to form carbonic acid.

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

It reduces to CO When passed through red hot coke

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

It can turn lime water milky

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Open in App

Solution

The correct options are
A
It is a colourless, odourless and tasteless gas

B
It dissolves in water to form carbonic acid.

C
It reduces to CO When passed through red hot coke

D
It can turn lime water milky

To answer this question, Let's look at the properties of $C O_{2}$ .

$C O_{2}$ is a colourless, odourless and tasteless gas and is about 1.5 times heavier than air.

Unlike $C O_{2}$ it is not poisonous in nature. However, it does not support life and animals die in it for want of oxygen.

$C O_{2}$ dissolves in water to form carbonic acid (H $_{2}$ CO $_{3}$ ) in very small amount, and most of the dissolved $C O_{2}$ remains loosely hydrated.
$C O_{2}$ ,therefore, is also known as carbonic anhydride.

$C O_{2 (g)} + H_{2}$ O $_{(l)}$ $\Leftrightarrow$ H $_{2}$ CO $_{3 (l)}$

Carbonic acid is a weak dibasic acid, highly unstable and thus cannot be isolated. It forms two series of salts, i.e. hydrogen carbonates and carbonates derived from the anions

HCO $_{3}^{⊖}$ and CO $_{3}^{2 -}$

H $_{2}$ CO $_{3 (a q)}$ + H $_{2}$ O $_{(l)}$ $⇌$ HCO $_{3 (a q)}^{⊖}$ + H $_{3}$ O $_{(a q)}^{⊖}$

HCO $_{3 (a q)}^{⊖}$ + H $_{2}$ O $_{(l)}$ $⇌$ CO $_{3 (a q)}^{2 -}$ + H $_{3}$ O $_{(a q)}^{⊖}$

When passed through red-hot coke, it is reduced to carbon monoxide, CO.

$C O_{2}$ , when bubbled through lime water, Ca(OH) $_{2}$ , initially turns lime water milky, However, when CO $_{2}$ is passed in excess, the solution
becomes clear or the milkiness disappears. On heating the clear solution, milkiness reappears. This is explained by the following reactions:

Ca(OH) $_{2}$ + CO $_{2}$ $\to$ CaCO $_{3}$ $↓$ + H $_{2}$ O

CaCO $_{3}$ + CO $_{2}$ + H $_{2}$ O $\to$ Ca(HCO $_{3}$ ) $_{2}$

Ca(HCO $_{3}$ ) $_{2 (a q)}$ $\to$ CaCO $_{3}$ $↓$ + CO $_{2}$ $↑$ + H $_{2}$ O

Calcium

Carbonate

(Insoluble)

So, all the options (a), (b) (c) and(d) are True.

Suggest Corrections