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Science · 2024 · 5 marks
CBSE 2024 · Region 2 · Set 1 · Q34
(a) (i) Give reason why carbon can neither form C^4+ cations nor C^4- anions but form covalent compounds. (ii) What is homologous series of carbon…
(a)(i)
Give reason why carbon can neither form $\displaystyle \mathrm{C}^{4+}$ cations nor $\displaystyle \mathrm{C}^{4-}$ anions but form covalent compounds.
(ii)
What is homologous series of carbon compound ? Write the molecular formula of any two consecutive members of homologous series of aldehydes.
(iii)
Draw the structure of the molecule of cyclohexane $\displaystyle \left(\mathrm{C}_{6} \mathrm{H}_{12}\right)$.
OR 34. (b) (i) Name a commercially important carbon compound having functional group -OH and write its molecular formula.
(ii)
Write chemical equation to show its reaction with
(1)
Sodium metal
(2)
Excess conc. sulphuric acid
(3)
Ethanoic acid in the presence of an acid catalyst
(4)
Acidified potassium dichromate Also write the name of the product formed in each case.
Marking-scheme solution
(i)
Carbon cannot form \(\displaystyle \mathrm{C}^{4+}\) cations because removal of $\displaystyle 4$ electrons from a carbon atom would require a large amount of energy and it cannot form \(\displaystyle \mathrm{C}^{4-}\) anion because it would be difficult for the nucleus with $\displaystyle 6$ protons to hold $\displaystyle 10$ electrons.
Thus it shares electrons to form covalent compounds.
A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain / series of compounds having same functional group and similar chemical properties.
\(\displaystyle \mathrm{CH}_{3} \mathrm{CHO}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{CHO}\)
(iii)
Structure of cyclohexane \(\displaystyle \left(\mathrm{C}_{6} \mathrm{H}_{12}\right)\)
(i)
Ethanol \(\displaystyle -\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\)
(ii)(1)
\(\displaystyle 2 \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+2 \mathrm{Na} \longrightarrow 2 \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}+\mathrm{H}_{2}\) Sodium Ethoxide
(2)
\(\displaystyle \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \xrightarrow{\text { Excess Conc. } \mathrm{H}_{2} \mathrm{SO}_{4}, 443 \mathrm{~K}} \underset{\text { Ethene }}{\mathrm{CH}}=\mathrm{CH}_{2}+\mathrm{H}_{2} \mathrm{O}\)
(3)
\(\displaystyle \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{CH}_{3} \mathrm{COOH} \xrightarrow{\text { Acid Catalyst }} \mathrm{CH}_{3} \mathrm{COOC}_{2} \mathrm{H}_{5}+\mathrm{H}_{2} \mathrm{O}\) Ester
(4)
\(\displaystyle \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \xrightarrow[\text { Ethanoic acid }]{\text { Acidified } \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}} \underset{\text { Ch }}{\mathrm{C} \mathrm{H}_{3} \mathrm{COOH}}\)
All Carbon and its Compounds questions2024 question paperNCERT solutions: Carbon and its CompoundsPractice Carbon and its Compounds →
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CBSE Class 10 Science past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.