Question

(a) Solution of a substance 'X' is used for testing carbon dioxide. Write the equation of the reaction of
'X' with carbon dioxide.
(b) How is obtained ? Write chemical equation.


CBSE Class X Science SA 2 (3 Marks)

Answer 1

a. X- calcium hydroxide --- Ca[OH]2

Ca[OH]2 + CO2 ------>  CaCO3 + H2O

b. Calcium hydroxide is obtained by the reaction of calcium oxide with water.

    CaO + H2O -------> Ca[OH]2 + Heat

Answer 2

(a) X = CALCIUM HYDROXIDE

For testing carbon dioxide, CALCIUM HYDROXIDE is used which is generally called as Lime Water.

The chemical formula of X is $\bold{\mathrm{Ca}(\mathrm{OH})_{2}}$

The chemical reaction with carbon dioxide is given below:

$\begin{matrix} Ca(OH)_{ 2 } \\ (Calcium\quad Hydroxide) \end{matrix}+\begin{matrix} CO_{ 2 } \\ (Carbon\quad dioxide) \end{matrix}\rightarrow \begin{matrix} CaCO_{ 3 } \\ (Calcium\quad Carbonate) \end{matrix}+\begin{matrix} H_{ 2 }O \\ (Water) \end{matrix}$

(b) X can be obtained in many ways:

For example:

1) Substance x is obtained by adding water and calcium oxide.

$\mathrm{CaO}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}$

2) X can be obtained by reaction of calcium with water.

$\mathrm{C a+2 H_{2} O \rightarrow C a(O H)_{2}+H_{2}}$