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Science · 2025 · 4 marks
CBSE 2025 · Region 4 · Set 1 · Q37
Common salt is a very important chemical compound for our daily life. It's chemical name is sodium chloride and it is used as a raw material in the…
Common salt is a very important chemical compound for our daily life. It's chemical name is sodium chloride and it is used as a raw material in the manufacture of caustic soda, washing soda, baking soda etc. It is also used in the preservation of pickles, butter, meat etc.
(i)
Name the acid and the base from which common salt can be obtained.
(ii)
State the nature (acidic/basic/neutral) of sodium chloride. Give reason for the justification for your answer.
(iii)
(A)
What happens when electric current is passed through an aqueous solution of sodium chloride (called brine)? Name the products obtained along with the corresponding places in the electrolytic cell where each of these products is obtained.
OR
(B)
How is washing soda obtained from sodium chloride? Give chemical equation of the reactions involved in the process.
Marking-scheme solution
(i)
Hydrochloric acid / HCl and Sodium hydroxide / NaOH
(ii)
-Neutral
as it is a salt of strong acid and strong base
(iii)
-Aqueous solution of sodium chloride(brine) decomposes (electrolysed) and produces:
NaOH solution near cathode
\(\displaystyle \mathrm{Cl}_{2}\) at anode
\(\displaystyle \mathrm{H}_{2}\) at cathode
Washing soda is obtained from sodium chloride by following reactions:
\(\displaystyle \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}+\mathrm{NH}_{3} \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}+\mathrm{NaHCO}_{3}\)
\(\displaystyle 2 \mathrm{NaHCO}_{3} \xrightarrow{\text { Heat }} \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}\)
Recrystallisation of sodium carbonate gives washing soda.
\(\displaystyle \mathrm{Na}_{2} \mathrm{CO}_{3}+10 \mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3} .10 \mathrm{H}_{2} \mathrm{O}\)
All Acids, Bases and Salts questions2025 question paperNCERT solutions: Acids, Bases and SaltsPractice Acids, Bases and Salts →
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CBSE Class 10 Science past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.