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Science · 2023 · 3 marks
CBSE 2023 · Region 5 · Set 3 · Q27
(a) Write a balanced equation to show the reaction that occurs when a piece of aluminium is dipped in a dilute solution of (i) sulphuric acid and…
(a)
Write a balanced equation to show the reaction that occurs when a piece of aluminium is dipped in a dilute solution of (i) sulphuric acid and (ii) sodium hydroxide.
(b)
Write the colour of the solution formed when copper oxide is treated with hydrochloric acid. Give reason for this observation.
Marking-scheme solution
(a) (i) \(\displaystyle 2 \mathrm{Al}+3 \mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}+3 \mathrm{H}_{2} \uparrow\)
(ii) \(\displaystyle 2 \mathrm{Al}+2 \mathrm{NaOH} \longrightarrow 2 \mathrm{NaAlO}_{2}+\mathrm{H}_{2} \uparrow\) (credit marks even if reaction is not balanced)
(b) •Blue green
due to the formation of Copper chloride /Copper (II)chloride / Cupric chloride
All Acids, Bases and Salts questions2023 question paperNCERT solutions: Acids, Bases and SaltsPractice Acids, Bases and Salts →
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CBSE Class 10 Science past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.