Chemistry 9th Chap 13 : Topic 9 - Maryam Publications

Chemistry Chapter 13 : Topic 9

Unsaturated Compounds

1 / 18

Which statement correctly defines an unsaturated compound in terms of carbon-carbon bonding?

A) A compound in which all carbon atoms are connected only by single bonds and contain maximum hydrogen atoms.

B) A compound that contains only carbon and oxygen atoms in equal ratio.

C) A compound formed only by ionic bonding between carbon and hydrogen atoms.

D) A compound in which one or more carbon-carbon bonds are double or triple bonds instead of only single bonds.

2 / 18

Why are alkenes and alkynes classified as unsaturated hydrocarbons?

A) Because they contain only single covalent bonds between all atoms.

B) Because they are always liquids at room temperature.

C) Because they do not contain hydrogen atoms at all.

D) Because they contain carbon-carbon multiple bonds (double or triple bonds).

3 / 18

Which of the following best distinguishes saturated compounds from unsaturated compounds?

A) Saturated compounds contain oxygen while unsaturated contain nitrogen.

B) Saturated compounds are always gases while unsaturated are always solids.

C) Saturated compounds contain only single bonds between carbon atoms, while unsaturated contain multiple bonds.

D) Saturated compounds are more reactive than unsaturated compounds.

4 / 18

Which of the following compounds is unsaturated?

A) Ethane (C₂H₆)

B) Methane (CH₄)

C) Propane (C₃H₈)

D) Ethene (C₂H₄)

5 / 18

What is the main reason unsaturated compounds are more reactive than saturated compounds?

A) They have weaker carbon-carbon single bonds.

B) They contain more hydrogen atoms.

C) They contain carbon-carbon double or triple bonds that can easily break for addition reactions.

D) They are always in gaseous state.

6 / 18

When bromine water is added to an unsaturated compound, what is the expected observation?

A) No change occurs.

B) It becomes milky.

C) It turns blue.

D) It gets decolorized (orange / brown color disappears).

7 / 18

Which type of bond is present in a carbon-carbon double bond?

A) One sigma and one pi bond

B) Only ionic bonds

C) Two sigma bonds

D) Two pi bonds

8 / 18

What happens to hydrogen content when a compound becomes unsaturated?

A) Hydrogen remains constant regardless of bonding.

B) Hydrogen decreases compared to saturated compounds with same carbon atoms.

C) Hydrogen becomes zero.

D) Hydrogen increases to maximum level.

9 / 18

Why do unsaturated hydrocarbons show addition reactions?

A) Because they contain carbonyl groups.

B) Because they are inert compounds.

C) Because they have only single bonds.

D) Because multiple bonds can break and allow atoms to add across them.

10 / 18

Which general formula represents alkenes?

A) CₙH₂ₙ₊₂

B) CₙHₙ

C) CₙH₂ₙ₋₂

D) CₙH₂ₙ

11 / 18

Which statement about ethyne (C₂H₂) is correct?

A) It has no carbon-carbon bonds.

B) It contains only single bonds.

C) It is a saturated hydrocarbon.

D) It contains a triple bond between carbon atoms.

12 / 18

Why do unsaturated compounds often burn with a sooty flame?

A) Due to higher carbon content and incomplete combustion

B) Due to absence of oxygen in structure

C) Due to high hydrogen content

D) Due to complete combustion only

13 / 18

Which property is NOT typical of unsaturated compounds?

A) Presence of only single bonds between carbon atoms

B) Ability to undergo addition reactions

C) Presence of double or triple bonds

D) Decolorization of bromine water

14 / 18

What is the structural effect of a carbon-carbon double bond?

A) Molecule becomes completely flexible

B) Bond becomes ionic in nature

C) Free rotation around bond is possible

D) Rotation is restricted making structure more rigid

15 / 18

Which of the following pairs correctly shows a saturated vs unsaturated compound?

A) Propane and Butane

B) Methane and Ethane

C) Methane and Propane

D) Ethane and Ethene

16 / 18

What happens during hydrogenation of an unsaturated compound?

A) Oxygen is added to form oxides.

B) Carbon atoms are removed.

C) Hydrogen is added across double or triple bonds converting it into a saturated compound.

D) Hydrogen is removed from the compound.

17 / 18

Which of the following best explains why unsaturated compounds are important in industry?

A) They do not react with other substances.

B) They cannot be converted into fuels.

C) They are chemically inert.

D) They easily undergo addition reactions to form useful products like polymers.

18 / 18

Which statement about carbon-carbon triple bonds is correct?

A) They contain one sigma and one pi bond.

B) They contain one sigma and two pi bonds.

C) They contain two sigma and one pi bond.

D) They contain only pi bonds.

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