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Science · 2023 · 5 marks
CBSE 2023 · Region 1 · Set 1 · Q34
(a) A saturated organic compound 'A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at 443 K, it forms…
A saturated organic compound 'A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at $\displaystyle 443$ K, it forms an unsaturated compound 'B' with molecular mass $\displaystyle 28$ u. The compound 'B' on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon 'C'.
(i)
Identify A, B and C.
(ii)
Write the chemical equations showing the conversion of A into B.
(iii)
What happens when compound C undergoes combustion ?
(iv)
State one industrial application of hydrogenation reaction.
(v)
Name the products formed when compound A reacts with sodium.
(i)
With the help of diagram, show the formation of micelles, when soap is applied on oily dirt.
(ii)
Take two test tubes X and Y with $\displaystyle 10$ mL of hard water in each. In test tube 'X', add few drops of soap solution and in test tube 'Y' add a few drops of detergent solution. Shake both the test tubes for the same period.
(1)
In which test tube the formation of foam will be more ? Why ?
(2)
In which test tube is a curdy solid formed ? Why ?
Marking-scheme solution
(a) (i) A: \(\displaystyle \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH} /\) Ethanol / Ethyl alcohol
B: \(\displaystyle \mathrm{CH}_{2}=\mathrm{CH}_{2} /\) Ethene
C: \(\displaystyle \mathrm{CH}_{3}-\mathrm{CH}_{3}\) / Ethane
(iii)
Carbon dioxide and water are produced and a large amount of heat is released /
\[\mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{O}_{2} \rightarrow 2 \mathrm{CO}_{2}+3 \mathrm{H}_{2} \mathrm{O}+\text { Heat }
\]
(iv)
Conversion of vegetable oil into fats.
(v) Sodium ethoxide and hydrogen
(b) (i)
(ii) ($\displaystyle 1$) • Test tube 'Y'.
Detergents are effective in hard water.
(2) • Test tube 'X'
Reaction between soap and calcium and magnesium salts of hard water form insoluble scum / due to formation of scum / insoluble ppt.
All Carbon and its Compounds questions2023 question paperNCERT solutions: Carbon and its CompoundsPractice Carbon and its Compounds →
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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.