Skip to content

(i) Name the compound formed… (Class 10 Science 2023, Q34b)

questionbuddy.in/q/cbse-10-science-2023-31-6-1-q34b-name-compound-formed-ethanol-heated

ScienceCBSE Class 10 · Board exam 2023, set 31/6/1 · 5 marks · Long answer

CBSE Class 10 Science 2023: question 34(b)

Set in the CBSE Class 10 board exam of 2023, paper 31/6/1, section D, question 34(b), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q34(b) · 5 marks · Long answerCarbon and its Compounds

(i) Name the compound formed when ethanol is heated at 443 K in the presence of conc. and draw its electron dot structure. State the role of conc. in this reaction.

(ii) What is hydrogenation? Explain it with the help of a chemical equation. State the role of this reaction in industry.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/6/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Heating ethanol with conc. H₂SO₄ removes a water molecule. What hydrocarbon is left?

Hint 2

Hydrogenation adds H₂ across a double bond. Think of how vegetable ghee is made.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (i) The compound formed is ethene, :

    ½ mark

  2. Electron dot structure (in words): The two carbon atoms share two pairs of electrons between them, forming a double bond. Each carbon also shares one electron pair with each of two hydrogen atoms: , with dots for the four C–H pairs.

    1 mark

  3. Conc. acts as a dehydrating agent: it removes water from ethanol.

    ½ mark

  4. (ii) Hydrogenation is the addition of hydrogen to unsaturated hydrocarbons, in the presence of a catalyst such as nickel or palladium, to form saturated compounds.

    1 mark

  5. Equation: , e.g.

    1 mark

  6. Role in industry: it is used to hydrogenate vegetable oils into vegetable ghee (fats) with saturated carbon chains.

    1 mark

Answer: (i) Ethene (CH₂=CH₂); conc. H₂SO₄ is a dehydrating agent. (ii) Hydrogenation is addition of H₂ to unsaturated compounds with Ni/Pd catalyst; used to convert vegetable oils into vegetable ghee.

Where the marks are

  • Names ethene (½ mark)
  • Correct electron dot structure (1 mark)
  • Role: dehydrating agent (½ mark)
  • Definition of hydrogenation (1 mark)
  • Equation with Ni/Pd catalyst (1 mark)
  • Industrial use: vegetable oil to ghee (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Carbon and its Compounds, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/6/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.