Hydrocarbons — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Hydrocarbons MCQs with step-by-step solutions (12 questions). Part of Carbon & Its Compounds. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Hydrocarbons · medium · theory
A compound made up of only carbon and hydrogen is called a:
A. hydrocarbon ✓ Correct
B. carbohydrate
C. carbonate
D. oxide
Solution: Hydrocarbons contain only carbon and hydrogen atoms (e.g. methane, ethane).
Q2 — Hydrocarbons · medium · theory
The simplest hydrocarbon, the main component of natural gas, is:
A. ethene (C₂H₄)
B. methane (CH₄) ✓ Correct
C. ethyne (C₂H₂)
D. ethane (C₂H₆)
Solution: Methane, CH₄, is the simplest hydrocarbon.
Q3 — Hydrocarbons · hard · theory
Hydrocarbons that contain only single bonds between carbon atoms are called:
A. saturated (alkanes) ✓ Correct
B. unsaturated (alkenes)
C. unsaturated (alkynes)
D. aromatic
Solution: Saturated hydrocarbons (alkanes) have only C–C single bonds.
Q4 — Hydrocarbons · hard · theory
A hydrocarbon containing a carbon–carbon double bond is:
A. propane (C₃H₈)
B. ethane (C₂H₆)
C. methane (CH₄)
D. ethene (C₂H₄) ✓ Correct
Solution: Ethene has a C=C double bond, making it an unsaturated alkene.
Q5 — Hydrocarbons · hard · theory
Ethyne (acetylene), used in welding torches, contains a carbon–carbon:
A. double bond
B. triple bond ✓ Correct
C. single bond
D. ionic bond
Solution: Ethyne (C₂H₂) has a C≡C triple bond.
Q6 — Hydrocarbons · medium · theory
When a hydrocarbon burns completely in plenty of air, the products are:
A. only carbon
B. carbon monoxide and hydrogen
C. carbon dioxide and water ✓ Correct
D. ammonia and water
Solution: Complete combustion of a hydrocarbon gives CO₂ and H₂O with the release of heat.
Q7 — Hydrocarbons · medium · theory
CNG and LPG, used as fuels, are mainly mixtures of:
A. metal oxides
B. salts
C. acids
D. hydrocarbons ✓ Correct
Solution: CNG (mostly methane) and LPG (propane/butane) are hydrocarbon fuels.
Q8 — Hydrocarbons · easy · theory
Which of the following is the simplest hydrocarbon?
A. Ethane (C2H6)
B. Methane (CH4) ✓ Correct
C. Ethyne (C2H2)
D. Ethene (C2H4)
Solution: Methane, CH4, has just one carbon atom and is the simplest of all hydrocarbons. The others each contain two carbon atoms.
Q9 — Hydrocarbons · easy · theory
Hydrocarbons are compounds made up of only which two elements?
A. Carbon and nitrogen
B. Carbon and hydrogen ✓ Correct
C. Hydrogen and oxygen
D. Carbon and oxygen
Solution: By definition a hydrocarbon contains only carbon and hydrogen. Adding other elements such as oxygen would give a different class of compound.
Q10 — Hydrocarbons · medium · theory
Which of the following is an unsaturated hydrocarbon?
A. Ethene (C2H4) ✓ Correct
B. Propane (C3H8)
C. Methane (CH4)
D. Ethane (C2H6)
Solution: Ethene (C2H4) has a carbon-carbon double bond, making it unsaturated. Methane, ethane and propane contain only single bonds and are saturated (alkanes).
Q11 — Hydrocarbons · medium · numerical
A saturated hydrocarbon (alkane) follows the general formula CnH(2n+2). How many hydrogen atoms are present in an alkane molecule that has 5 carbon atoms?
A. 11
B. 10
C. 5
D. 12 ✓ Correct
Solution: Substituting n = 5 into 2n + 2 gives 2(5) + 2 = 12 hydrogen atoms. The molecule is C5H12 (pentane).
Q12 — Hydrocarbons · hard · numerical
An alkene has the general formula CnH2n. A particular alkene has a molecular mass of 42 (take C = 12, H = 1). Its molecular formula is:
A. C4H8
B. C3H8
C. C2H4
D. C3H6 ✓ Correct
Solution: For CnH2n the mass is 12n + 2n = 14n. Setting 14n = 42 gives n = 3, so the formula is C3H6 (propene), whose mass is 3(12) + 6 = 42. C3H8 is rejected because it is an alkane, not an alkene.