✓ Board-verified
Science · 2026 · 5 marks
CBSE 2026 · Region 4 · Set 3 · Q29
Attempt either option (A) or (B): (A) (i) Carbon cannot form C^4+ cation and C^4- anion. Explain. (ii) Define homologous series of carbon compounds.…
Attempt either option (A) or (B) :
(i)
Carbon cannot form $\displaystyle \mathrm{C}^{4+}$ cation and $\displaystyle \mathrm{C}^{4-}$ anion. Explain.
(ii)
Define homologous series of carbon compounds. Why are the melting and boiling points of $\displaystyle \mathrm{C}_{4} \mathrm{H}_{10}$ higher than $\displaystyle \mathrm{C}_{3} \mathrm{H}_{8}$ or $\displaystyle \mathrm{C}_{2} \mathrm{H}_{6}$ ?
(iii)
What happens when ethanol is heated with acidified potassium dichromate? $\displaystyle \mathbf{2}+\mathbf{2}+\mathbf{1}$
(i)
How would you name the following : I.
II. $\displaystyle \mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}$
(ii)
When ethanol reacts with ethanoic acid in the presence of conc. $\displaystyle \mathrm{H}_{2} \mathrm{SO}_{4}$, a substance with sweet smell is produced. Answer the following : I. State the class of compounds to which the sweet smelling compounds belong. II. Write the chemical equation for the reaction.
Marking-scheme solution
(A)(i)
Carbon cannot form \(\displaystyle \mathrm{C}^{4+}\) cation because removal of four electrons is energetically not possible. Carbon cannot form \(\displaystyle \mathrm{C}^{4-}\) anion because nucleus with six protons cannot hold ten electrons.
(ii)
A series of compounds in which the same functional group substitutes for hydrogen in carbon chain is called a homologous series.
Because of higher molecular mass of \(\displaystyle \mathrm{C}_{4} \mathrm{H}_{10}\) than \(\displaystyle \mathrm{C}_{3} \mathrm{H}_{8}\) or \(\displaystyle \mathrm{C}_{2} \mathrm{H}_{6}\).
(iii) Ethanoic acid / acetic acid / \(\displaystyle \mathrm{CH}_{3} \mathrm{COOH}\) is formed /
\[\mathrm{CH}_{4}-\mathrm{CH}_{2} \mathrm{OH} \xrightarrow[\text { Or acidifled } \mathrm{K} K_{2} \mathrm{Cr}_{2} \mathrm{O}+\text { Heal }]{\text { Alkaline } \mathrm{KMnO}_{4}+\text { Heat }} \mathrm{CH}_{8} \mathrm{COOH}
\]
(i) I. Propanal
II. Propyne
(ii) I. Ester group
Physics
All Carbon and its Compounds questions2026 question paperNCERT solutions: Carbon and its CompoundsPractice Carbon and its Compounds →
More from Carbon and its Compounds
- The number of single and double bonds present in a molecule of benzene (C_6 H_6) respectively, are:2024
- Which one of the following hydrocarbons is different from the others?2024
- Draw two different possible structures of a saturated hydrocarbon having four carbon atoms in its molecule. What are these two structures of the…2022
- Hydronium ions are formed by the reaction between:2023
- The number of electrons in the outermost shell of the atom of a non-metal can be:2023
- (i) Butane had both Carbon - Carbon bonds as well as Carbon - Hydrogen bonds. Draw its structural formula and state the number of (1) C-H bonds and…2023
- The melting and boiling points of carbon compounds are generally low and they are largely non-conductors of electricity. State two conclusions based…2024
- Select the correct option(s) in the following table:2023
CBSE Class 10 Science past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.