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Chapter 4: Carbon and its Compounds — Online MCQ Test

Q: What is the atomic number of carbon, and how many valence electrons does it have?

Answer: B. Atomic number 6, with 4 valence electrons — Carbon has atomic number 6 (6 protons) and electron configuration 2,4, giving it 4 valence electrons in its outermost shell.

Q: Consider the functional groups: -OH, -CHO, -COOH, and -CO-. Which one is present in carboxylic acids?

Answer: C. -COOH — The carboxyl group (-COOH) is the functional group characteristic of carboxylic acids, and these compounds are named with the suffix '-oic acid'.

Q: The general formula for alkynes (unsaturated hydrocarbons with triple bonds) is CₙH₂ₙ₋₂. If an alkyne has 6 carbon atoms, how many hydrogen atoms does it have?

Answer: A. 10 — Using the formula CₙH₂ₙ₋₂ with n=6: H = 2(6)-2 = 10. Therefore, a six-carbon alkyne has the formula C₆H₁₀.

Q: A hydrocarbon has the formula CₓHᵧ. If it follows the alkane pattern and contains only single bonds, and has 8 carbon atoms, what is the value of y?

Answer: C. 18 — For an alkane with n=8 carbons, using the formula CₙH₂ₙ₊₂: H = 2(8)+2 = 18. Therefore, the compound is C₈H₁₈ (octane).

SCIENCE · CLASS 10th · Karnataka State Board

Practice Chapter 4: Carbon and its Compounds with a free chapter-wise online MCQ test for Karnataka State Board CLASS 10th SCIENCE. This chapter covers: 1. Covalent Bonding in CarbonCarbon has an atomic number of 6, meaning it has 4 valence electrons.It cannot gain 4 electrons to form \(C^{4-}\) (nucleus cannot hold 10 electrons) o.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 4: Carbon and its Compounds — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 10th SCIENCE — Chapter 4: Carbon and its Compounds, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is the atomic number of carbon, and how many valence electrons does it have?

A. Atomic number 4, with 2 valence electrons
B. Atomic number 6, with 4 valence electrons ✓
C. Atomic number 8, with 6 valence electrons
D. Atomic number 6, with 2 valence electrons

Answer: B. Atomic number 6, with 4 valence electrons
Carbon has atomic number 6 (6 protons) and electron configuration 2,4, giving it 4 valence electrons in its outermost shell.

Why does carbon form covalent bonds instead of ionic bonds?

A. Carbon is a metal and always forms ionic bonds
B. Carbon cannot lose 4 electrons to form C⁴⁺ (too much energy) or gain 4 electrons to form C⁴⁻ (nucleus cannot hold 10 electrons) ✓
C. Carbon prefers to remain neutral and does not bond at all
D. Carbon can only form bonds with hydrogen atoms

Answer: B. Carbon cannot lose 4 electrons to form C⁴⁺ (too much energy) or gain 4 electrons to form C⁴⁻ (nucleus cannot hold 10 electrons)
Carbon forms covalent bonds by sharing electrons because forming C⁴⁺ requires excessive energy and forming C⁴⁻ is impossible as the nucleus cannot hold 10 electrons stably.

Consider the functional groups: -OH, -CHO, -COOH, and -CO-. Which one is present in carboxylic acids?

A. -OH
B. -CHO
C. -COOH ✓
D. -CO-

Answer: C. -COOH
The carboxyl group (-COOH) is the functional group characteristic of carboxylic acids, and these compounds are named with the suffix '-oic acid'.

The general formula for alkynes (unsaturated hydrocarbons with triple bonds) is CₙH₂ₙ₋₂. If an alkyne has 6 carbon atoms, how many hydrogen atoms does it have?