Q1. [4]
Carbon is a versatile element that forms the basis of all living organisms and many of the things we use. A large variety of compounds is formed because of its tetravalency. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements.
Answer the following questions :
- (a) What are hydrocarbons ? [1]
- (b) List two properties by virtue of which carbon can form a large number of compounds. [1]
- (c) Answer either (i) or (ii): [2]
Previously asked in CBSE board exam
2024 31/5/1 Q37
Generated by claude-sonnet-4-6 · 2026-06-15 06:48 · grounding stimulus
I notice that sub-question (c) is incomplete — options (i) and (ii) are missing from the question. I'll answer (a) and (b) fully, and note the gap for (c).
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Model Answer
(a) Compounds of carbon formed exclusively with hydrogen are called hydrocarbons.
(Example: methane, CH₄)
(b) The two properties are:
- Tetravalency — Carbon has a valency of 4, allowing it to bond with four other atoms.
- Catenation — Carbon has the unique ability to bond with other carbon atoms to form long chains, branches, and rings.
(c) (Sub-question (c) cannot be answered as options (i) and (ii) were not provided in the question. Please supply the missing options for a complete answer.)
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Explanation
- For (a): Examiners expect the definition + at least one example for full credit.
- For (b): These are the two standard properties asked repeatedly in CBSE boards — catenation and tetravalency. Both terms must be written by name; just describing them without the term may cost marks.
- For (c): Since the options were cut off in the question, no answer can be framed. In the actual exam paper, choose either (i) or (ii) — not both — and write approximately 40–50 words for the 2-mark part.
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