Class 11 - Chemistry - Alkanes - Questions and Answers #hydrocarbons #alkanes #organicchemistry #class11chemistry #eduvictors

Class 11 - Chemistry - Alkanes - Questions and Answers

Chapter: Hydrocarbons

Very Short Answer Based Questions (VSQA)

Q1: What are hydrocarbons?

Answer: Hydrocarbons are the compounds of carbon and hydrogen are obtained from coal and petroleum.

Q2: What are alkanes?

Answer: Alkanes are saturated open-chain hydrocarbons containing C—C single bonds.

Q3: How C-C atoms are joined in alkanes? What are the lengths of C-C and C-H bonds?

Answer:  In alkanes, C-atoms are tetrahedrally joined together in which C—C and C—H bond lengths are 154 pm and 112 pm respectively.

Q4: What type of hybridisation is found in C-atoms of alkanes?

Answer: All the C-atoms in alkanes are sp³ -hybridised.

Q5: Draw the structure of a methane molecule?

Answer:

Q6: What is the generic formula for alkanes?

Answer: CₙH₂ₙ₊₂

Q7: List the names of the first ten alkane members

Answer: 

No. of C-atoms	Formula (I)	Formula (II)	Name
1	CH₄	CH₄	Methane
2	C₂H₆	CH₃CH₃	Ethane
3	C₃H₈	CH₃CH₂CH₃	Propane
4	C₄H₁₀	CH₃(CH₂)₂CH₃	Butane
5	C₅H₁₂	CH₃(CH₂)₃CH₃	Pentane
6	C₆H₁₄	CH₃(CH₂)₄CH₃	Hexane
7	C₇H₁₆	CH₃(CH₂)₅CH₃	Heptane
8	C₈H₁₈	CH₃(CH₂)₆CH₃	Octane
9	C₉H₂₀	CH₃(CH₂)₇CH₃	Nonane
10	C₁₀H₂₂	CH₃(CH₂)₈CH₃	Decane

Q8: Are alkanes polar or no-polar molecules?

Answer: Non-polar molecules.

Q9: What are the physical states of Alkane members?

Answer: The first four members, C₁ to C₄ are gases. C₅ to C₁₇ are liquids containing 18 carbon atoms or more solids at room temperature.

Q10: What is the colour and odour of alkanes?

Answer: These are colourless and odourless.

Q11: Boiling point of alkanes ________ with the increase in molecular mass. (Fill in the blanks)

Answer: increases

Q12:  Alkanes can have _________ number of conformations by rotation around C—C single bonds.  (Fill in the blanks)

Answer: infinite

Q13: Alkanes with an even number of carbon atoms have ________ melting points than those with an odd number of carbon atoms due to symmetry. (Fill in the blanks)

Answer: higher

Q14: What type of isomerism is shown by alkanes?

Answer: Alkanes exhibit chain isomerism. 

👉See Also:

Colour of Compounds/Salts
Structure Of Atom - Important Points To Remember

Mole Concept
Discoveries In Atomic Structure
Law of Chemical Combinations
Thermodynamics
Equilibrium - What are reversible and irreversible reactions?
Four New Elements Added in Periodic Table
Quiz On Gases

Ch 9 - Hydrogen (Very Short Q & A)

Ch14 - Environmental Chemistry - Atmospheric Pollution (Concept Points)

Chemistry Half Year Question Paper (2018-19)

Soaps and Detergents
Periodic Table